Ronald L. Dalman MD

Surgery - Vascular Surgery

Bio

Bio

Dr. Dalman has served as a faculty member of Stanford Surgery since 1992, and has directed the Vascular Surgery program since 2005. He currently holds the Chidester Professorship in the Department of Surgery. His clinical interests include management of aortic diseases and lower extremity circulatory disorders, including limb salvage. He is a member of the Vascular Surgery Board, American Board of Surgery, and a past member of the Residency Review Committee for Surgery, ACGME. At Stanford Health Care he serves as Co-Director and Chief Quality Officer for the Cardiovascular Service Line. At the School of Medicine, Dr. Dalman is a Steering Committee and founding member of the Cardiovascular Institute (CVI), currently serving as co-Principle Investigator of the CVI's NHLBI T32 "Mechanisms and Innovation in Vascular Disease" training grant. Prior to his appointment as Chief of Vascular Surgery at Stanford Health Care, Dalman served as Chief of Vascular Surgery at the Veterans Affairs Palo Alto Health Care System for 14 years. Dr. Dalman's research laboratory studies the pathophysiology of abdominal aortic aneurysm (AAA) disease, a leading cause of death in developed and developing countries worldwide, and is actively engaged in identifying and validating new treatment measures for AAA. Dr. Dalman's laboratory has received continuous research funding from the National Institutes of Health since 1999, and collaborates with leading investigators in AAA disease worldwide.

Links

Research & Scholarship

Current Research and Scholarly Interests

We are investigating the biologic and mechanical basis of aneurysmal degeneration of the aorta. We use molecular, imaging and computer modeling modalities to identify novel treatment strategies for small AAAs and hybrid drug/device surgical solutions for larger AAAs.

By extension we are keenly interested in new surgical technology and its application to aneurysmal and occlusive arterial and venous diseases. To this end we have completed over 50 drug and device clinical trials from dozens of governmental and commercial sponsors in our SUMC and VA clinical practices. We are currently enrolling patients in over a dozen clinical trials at both sites. Please review our website (vascular.stanford.edu) for updates regarding clinical trials and eligibility criteria.

Clinical Trials

An abdominal aortic aneurysm (AAA) is a weakened and enlarged area in the abdominal aorta,
which is a large blood vessel in the abdomen. If an AAA ruptures, it can be
life-threatening. Research has shown that sedentary individuals are at increased risk of
developing AAAs. This study will evaluate the effectiveness of an exercise program at
limiting the growth of small AAAs in older individuals.

Stanford is currently not accepting patients for this trial.For more information, please contact Ronald Dalman, (650) 723 - 2169.

The purpose of this study is to evaluate the long-term safety and efficacy of the Xact™
Rapid Exchange Carotid Stent System used in conjunction with the Emboshield® Pro Rapid
Exchange Embolic Protection System (Generation 5) and the Emboshield® BareWire™ Rapid
Exchange Embolic Protection System (Generation 3), in the treatment of atherosclerotic
carotid artery disease in high-surgical risk subjects.

Stanford is currently not accepting patients for this trial.For more information, please contact Ronald Dalman, (650) 725 - 5227.

The purpose of this study is to compare endovascular repair using any FDA approved Medtronic
AAA Stent Graft System versus surveillance in subjects with smaller abdominal aortic
aneurysms (AAA)(4-5CM), with respect to AAA rupture and AAA related deaths.

Stanford is currently not accepting patients for this trial.For more information, please contact Jason Lee, (650) 725 - 5227.

Purpose of this study: The purpose of the study is to evaluate the safety and effectiveness
of the Lombard Medical endovascular Aorfix™ AAA bifurcated stent graft in the treatment of
abdominal aortic, aorto-iliac and common iliac aneurysms with anatomies including angled
aorta, angled aneurysmal body, or both, between 0° and 90°.
Study hypothesis: The primary efficacy hypothesis is the proportion of grafts remaining free
from endoleak, migration, and fracture at 12 months.
Efficacy: The 12 month, all cause mortality rate in the Aorfix™ group will be non-inferior
to the 12 month, all cause mortality rate in the Open Control group.
Safety: The rates of early serious adverse events between 0 and 30 days post-operative in
the Aorfix™ groups will be non-inferior to the early serious adverse event rates between 0
and 30 days post-operative in the Open Control group.

Stanford is currently not accepting patients for this trial.For more information, please contact Jason Lee, (650) 725 - 5227.

The PRESERVE-Zenith® Iliac Branch System Clinical Study is a clinical trial to study the
safety and effectiveness of the Zenith® Branch Endovascular Graft-Iliac Bifurcation in
combination with the Zenith® Connection Endovascular Stent/ConnectSX™ covered stent in the
treatment of aorto-iliac and iliac aneurysms.

The purpose of the study is to demonstrate the long term safety and effectiveness of the
Endurant Stent Graft System for the endovascular treatment of infrarenal abdominal aortic
aneurysms in a post-approval environment, through the endpoints established in this
protocol.
The clinical objective of the study is to evaluate the long term safety and effectiveness of
the Endurant Stent Graft System assessed at 5 years through freedom from Aneurysm-Related
Mortality (ARM).

Stanford is currently not accepting patients for this trial.For more information, please contact Ronald Dalman, (650) 725 - 5227.

The purposes of this study is to 1) Provide additional information that the commercially
available Abbott Vascular Carotid Stent Systems and Embolic Protection Systems can be used
successfully by a wide range of physicians under commercial use conditions. 2) Provide an
ongoing post-market surveillance mechanism for documentation of clinical outcomes and for
possible extension of the Centers for Medicare and Medicaid Services (CMS) coverage to a
broader group of patients.

Stanford is currently not accepting patients for this trial.For more information, please contact Ronald Dalman, (650) 725 - 5227.

The primary aim of this study is to determine if doxycycline (100 mg bid) will inhibit (by
at least 40%) the increase in greatest transverse diameter of small abdominal aortic
aneurysms (3.5-5.0 cm in men, 3.5-4.5 cm in women) over a 24-month period of observation in
comparison to a placebo-treated control group.

Study of the Effectiveness of Telmisartan in Slowing the Progression of Abdominal Aortic AneurysmsRecruiting

The purpose of this study is to determine if telmisartan is effective in slowing the
progression of abdominal aortic aneurysms and reducing circulating concentrations of
Abdominal Aortic Aneurysms (AAA) biomarkers.

Abstract

In population-based studies performed on multiple continents during the past two decades, diabetes mellitus has been negatively associated with the prevalence and progression of abdominal aortic aneurysm (AAA) disease. We investigated the possibility that metformin, the primary oral hypoglycemic agent in use worldwide, may influence the progression of AAA disease.Preoperative AAA patients with diabetes were identified from an institutional database. After tabulation of individual cardiovascular and demographic risk factors and prescription drug regimens, odds ratios for categorical influences on annual AAA enlargement were calculated through nominal logistical regression. Experimental AAA modeling experiments were subsequently performed in normoglycemic mice to validate the database-derived observations as well as to suggest potential mechanisms of metformin-mediated aneurysm suppression.Fifty-eight patients met criteria for study inclusion. Of 11 distinct classes of medication considered, only metformin use was negatively associated with AAA enlargement. This association remained significant after controlling for gender, age, cigarette smoking status, and obesity. The median enlargement rate in AAA patients not taking oral diabetic medication was 1.5 mm/y; by nominal logistic regression, metformin, hyperlipidemia, and age ≥70 years were associated with below-median enlargement, whereas sulfonylurea therapy, initial aortic diameter ≥40 mm, and statin use were associated with above-median enlargement. In experimental modeling, metformin dramatically suppressed the formation and progression, with medial elastin and smooth muscle preservation and reduced aortic mural macrophage, CD8 T cell, and neovessel density.Epidemiologic evidence of AAA suppression in diabetes may be attributable to concurrent therapy with the oral hypoglycemic agent metformin.

Abstract

Visceral arteries are commonly involved in endovascular repair of complex abdominal aortic aneurysms (AAAs). To improve repair techniques and reduce long-term complications involving visceral arteries, it is crucial to understand in vivo arterial geometry and the deformations due to visceral organ movement with respiration. This study quantifies deformation of the celiac, superior mesenteric (SMA), and renal arteries during respiration and correlates the deformations with diaphragmatic excursion.Sixteen patients with small AAAs underwent magnetic resonance angiography during inspiratory and expiratory breathholds. From geometric models of the aorta and visceral arteries, vessel length, branch angle, curvature, and positions were computed, along with degree of diaphragmatic excursion as indicated by kidney translation.From inspiration to expiration, the celiac artery exhibited axial shortening of 4.8 ± 6.4% (P 0.50). Correlation of the LRA with the left kidney was greater than that of the RRA with the right kidney.The celiac artery exhibited less branch angle change, and greater axial and curvature deformations than the other visceral arteries, due to the vicinity to the liver and influence of the median arcuate ligament. Correlation between visceral arteries and kidney translations revealed that diaphragmatic excursion affects vessel mobility. Weaker correlation of the RRA to the right kidney indicates mechanical shielding from the inferior vena cava.

Abstract

The durability of stent grafts may be related to how procedures and devices alter native anatomy. We aimed to quantify and compare renal artery geometry before and after fenestrated (F-) or snorkel/chimney (Sn-) endovascular aneurysm repair (EVAR).Forty patients (75 ± 6 years) underwent computed tomographic angiography before and after F-EVAR (n = 21) or Sn-EVAR (n = 19), with a total of 72 renal artery stents. Renal artery geometry was quantified using three-dimensional model-based centerline extraction. The stented length was computed from the vessel origin to the stent end. The branch angle was computed relative to the orthogonal configuration with respect to the aorta. The end-stent angle was computed relative to the distal native renal artery. Peak curvature was defined as the inverse of the radius of the circumscribed circle at the highest curvature within the proximal portion from the origin to the stent end and the distal portion from the stent end to the first renal artery bifurcation.Sn-renals had greater stented length compared to F-renals (P < .05). From the pre- to the postoperative period, the origins of the Sn-left renal artery and right renal artery (RRA) angled increasingly downward by 21 ± 19° and 13 ± 17°, respectively (P < .005). The F-left renal artery and RRA angled upward by 25 ± 15° and 14 ± 15°, respectively (P

Abstract

Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1+/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1+/- mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1-beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease.

Abstract

Complex endovascular aneurysm repair (EVAR) involves extension of the proximal aortic seal zone with preservation of branch vessel patency, thereby expanding the applicability of endografting from the infrarenal to the suprarenal aorta. Snorkel/chimney (Sn-EVAR) and fenestrated EVAR (f-EVAR) serve as the two most commonly utilized advanced endovascular techniques to combat hostile proximal neck anatomy. The purpose of this article is to describe the principles and evolution of these advanced endovascular strategies, technical considerations, and results of sn- and f-EVAR in the management of challenging neck anatomy in abdominal aortic aneurysm disease.

Abstract

This study seeks to determine the risks for obstructive sleep apnea (OSA) and cardiometabolic disease (CMR) in elderly patients with mild-moderate abdominal aortic aneurysms (AAA).Three hundred two elderly patients with diagnosed small AAA disease were subjects. CMR was assessed by several biomarkers, with special focus on the Lipid Accumulation Product (LAP) and the Triglyceride-Glucose Index (TyG Index), two validated screening indicators of CMR related to central obesity and insulin resistance, respectively. Analysis of OSA risk was assessed with the Berlin Questionnaire.The patients (60.6 %) had increased risk of OSA; those at high risk also were at increased (p

Abstract

This study quantified the geometry and respiration-induced deformation of abdominal branch vessels and stents after fenestrated (F-) and snorkel (Sn-) endovascular aneurysm repair (EVAR).Twenty patients (80% male; mean age, 75.2 ± 7.4 years; mean aneurysm diameter, 6.2 ± 1.8 cm) underwent computed tomography angiography during inspiratory and expiratory breath hold protocols after F-EVAR (n = 11) or Sn-EVAR (n = 9). Centerlines for the aorta and visceral vessels were extracted from three-dimensional models. Branch angles were computed relative to the orthogonal plane at the branch ostia, and end-stent angles of the left renal artery (LRA) and right renal artery (RRA) were computed relative to the distal stent orientation. The radius of peak curvature was defined by the circumscribed circle at the highest curvature.Sn-renal branches were more downward-angled than F-renal branches (P < .04). At the distal ends of the RRA stents, Sn-RRAs were angled greater than F-RRAs (P < .03) and had a smaller radius of peak curvature (P < .03). With expiration, the end-stent angle of Sn-LRAs increased by 4° ± 4° (P < .02) and exhibited a significant reduction of radius of curvature (P < .04). The unstented celiac arteries were more downward-angled (P < .02, inspiration), with a smaller radius of curvature (P < .00001), than the unstented superior mesenteric arteries. With expiration, the celiac arteries angled upwards by 9° ± 9° (P < .0005), which was greater than the superior mesenteric arteries (P < .03). At a median postoperative follow-up of 12.6 months (range, 1.0-37.1 months), branch vessel patency was 100%, serum creatinine levels remained stable, and one reintervention was required for a type III endoleak at the main body-LRA stent interface.Sn-renals were angled more inferiorly at the branch and more angulated at the stent end than F-renals due to stent placement strategies. Sn-LRAs exhibited a significant change in end-stent angle and curvature during respiration, a finding that may compromise long-term durability for parallel stent graft configurations. Further investigation is warranted to better optimize anatomic, patient, and branch vessel stent selection between fenestrated and snorkel strategies and their relationship to long-term patency.

Abstract

Quantifying lifetime physical activity using self-reported measures is challenging due to reliance on recall, especially in older populations. The purpose of this study was to determine the 1-year reproducibility of the Veterans Physical Activity Questionnaire (VAPAQ) in a cohort of patients with documented abdominal aortic aneurysm disease (AAA).Subjects included men (n = 52) and women (n = 3) enrolled in AAA STOP, a randomized trial designed to test the ability of supervised exercise training to modify AAA biology and early disease progression.The overall correlation coefficient for lifetime recreational energy expenditure between the 2 examinations was 0.93 (P < .001), with an overall difference of 26 kcal/week, a typical error (standard deviation of the differences) of 171 kcals/week, and a coefficient of variation (CV) of 15.5%.The VAPAQ is a reproducible tool to quantify lifetime energy expenditure in older adults with documented vascular disease.

Abstract

Experimental studies suggest that angiotensin II plays a central role in the pathogenesis of abdominal aortic aneurysm. This trial aims to evaluate the efficacy of the angiotensin receptor blocker telmisartan in limiting the progression of abdominal aortic aneurysm.Telmisartan in the management of abdominal aortic aneurysm (TEDY) is a multicentre, parallel-design, randomised, double-blind, placebo-controlled trial with an intention-to-treat analysis. We aim to randomly assign 300 participants with small abdominal aortic aneurysm to either 40 mg of telmisartan or identical placebo and follow patients over 2 years. The primary endpoint will be abdominal aortic aneurysm growth as measured by 1) maximum infra-renal aortic volume on computed tomographic angiography, 2) maximum orthogonal diameter on computed tomographic angiography, and 3) maximum diameter on ultrasound. Secondary endpoints include change in resting brachial blood pressure, abdominal aortic aneurysm biomarker profile and health-related quality of life. TEDY is an international collaboration conducted from major vascular centres in Australia, the United States and the Netherlands.Currently, no medication has been convincingly demonstrated to limit abdominal aortic aneurysm progression. TEDY will examine the potential of a promising treatment strategy for patients with small abdominal aortic aneurysms.Australian and Leiden study centres: Australian New Zealand Clinical Trials Registry ACTRN12611000931976 , registered on 30 August 2011; Stanford study centre: clinicaltrials.gov NCT01683084 , registered on 5 September 2012.

Abstract

Chemokine receptor CCR2 mediates monocyte mobilization from the bone marrow (BM) and subsequent migration into target tissues. The degree to which CCR2 is differentially expressed in leukocyte subsets, and the contribution of CCR2 to these leukocyte mobilization from the BM are poorly understood. Using red fluorescence protein CCR2 reporter mice, we found heterogeneity in CCR2 expression among leukocyte subsets in varying tissues. CCR2 was highly expressed by inflammatory monocytes, dendritic cells, plasmacytoid dendritic cells and NK cells in all tissues. Unexpectedly, more than 60% of neutrophils expressed CCR2, albeit at low levels. CCR2 expression in T cells, B cells and NK T cells was greatest in the BM compared to other tissues. Genetic CCR2 deficiency markedly sequestered all leukocyte subsets in the BM, with reciprocal reduction noted in the peripheral blood and spleen. CCR2 inhibition via treatment with CCR2 signaling inhibitor propagermanium produced similar effects. Propagermanium also mitigated lipopolysaccharide-induced BM leukocyte egress. Consistent with its functional significance, CCR2 antibody staining revealed surface CCR2 expression within a subset of BM neutrophils. These results demonstrate the central role CCR2 plays in mediating leukocyte mobilization from the BM, and suggest a role for CCR2 inhibition in managing monocytes/macrophages-mediated chronic inflammatory conditions.

Abstract

Abdominal aortic aneurysm (AAA) is often accompanied by in traluminal thrombus (ILT), which complicates AAA progression and risk of rupture. Patient-specific computational fluid dynamics modeling of 10 small human AAA was performed to investigate relations between hemodynamics and ILT progression. The patients were imaged using magnetic resonance twice in a 2- to 3-yr interval. Wall content data were obtained by a planar T1-weighted fast spin echo black-blood scan, which enabled quantification of thrombus thickness at midaneurysm location during baseline and followup. Computational simulations with patient-specific geometry and boundary conditions were performed to quantify the hemodynamic parameters of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and mean exposure time at baseline. Spatially resolved quantifications of the change in ILT thickness were compared with the different hemodynamic parameters. Regions of low OSI had the strongest correlation with ILT growth and demonstrated a statistically significant correlation coefficient. Prominent regions of high OSI (>0.4) and low TAWSS (<1 dyn/cm(2)) did not appear to coincide with locations of thrombus deposition.

Abstract

Independent of their blood pressure lowering effect, ACE inhibitors are thought to reduce vascular inflammation. The clinical relevance of this effect is unclear with the current knowledge. Abdominal aortic aneurysms (AAA) are characterized by a broad, non-specific inflammatory response, and thus provide a clinical platform to evaluate the anti-inflammatory potential of ACE inhibitors.Eleven patients scheduled for open AAA repair received ramipril (5 mg/day) during 2-4 weeks preceding surgery. Aortic wall samples were collected during surgery, and compared to matched samples obtained from a biobank. An anti-inflammatory potential was evaluated in a comprehensive analysis that included immunohistochemistry, mRNA and protein analysis. A putative effect of ACE inhibitors on AAA growth was tested separately by comparing 18-month growth rate of patients on ACE inhibitors (n = 82) and those not taking ACE inhibitors (n = 204). Ramipril reduces mRNA expression of multiple pro-inflammatory cytokines such as IL-1β, IL-6, IL-8, TNF -α, Interferon-[Formula: see text], and MCP-1, as well as aortic wall IL-8 and MCP-1 (P = 0.017 and 0.008, respectively) protein content. The is followed by clear effects on cell activation that included a shift towards anti-inflammatory macrophage (M2) subtype. Evaluation of data from the PHAST cohort did not indicate an effect of ACE inhibitors on 18-month aneurysm progression (mean difference at 18 months: -0.24 mm (95% CI: -0.90-0.45, P = NS).ACE inhibition quenches multiple aspects of vascular inflammation in AAA. However, this does not translate into reduced aneurysm growth.Nederlands Trial Register 1345.

Abstract

The snorkel approach for endovascular aneurysm repair (EVAR) has been found to be a safe and viable alternative to open repair for juxtarenal abdominal aortic aneurysms with good short-term outcomes. Concerns about long-term durability and renal branch patency with this technique have been raised with the increasing availability of fenestrated devices. We sought to evaluate renal function changes in patients undergoing "snorkel" EVAR (sn-EVAR).Patients who underwent sn-EVAR from 2009 to 2012 were included in this analysis. Creatinine values were obtained throughout the patient's preoperative, perioperative, and postoperative course. Glomerular filtration rate (GFR) was estimated by the simplified Modification of Diet in Renal Disease formula. Acute renal dysfunction was analyzed according to the RIFLE (Risk, Injury, Failure, Loss, End stage) criteria, whereas chronic renal dysfunction was stratified by the chronic kidney disease staging system.Forty-three consecutive patients underwent sn-EVAR (31 double renal, 12 single renal) for juxtarenal aortic aneurysms. Mean follow-up time was 21 months. Mean aneurysm size was 6.6 cm (range, 5.1-10.5 cm) with anatomy not suitable for treatment with standard EVAR (mean neck length, 1.6 mm); 74 renal snorkel stents were placed in these patients with a 2-year primary patency of 95%. On average, the cohort at baseline was stratified as having moderate renal dysfunction. Mean baseline, maximum postoperative, and latest follow-up creatinine concentrations were 1.20, 1.49, and 1.43, respectively (P = .004). Mean baseline, maximum postoperative, and latest follow-up GFRs were 57.4, 47.8, and 49.2, respectively (P = .014). With use of RIFLE criteria, 14 patients (32.6%) experienced some form of acute kidney injury, although 10 of these patients (23.3%) were classified as mild (25%-50% decline in GFR). On analysis without the RIFLE criteria, 21.4% of patients had postoperative creatinine concentration >1.5 mg/dL, 28.6% had postoperative creatinine concentration increase >30%, and 28.6% had postoperative GFR decline >30%. For the entire study cohort at latest follow-up, 51% experienced no decline of chronic renal dysfunction and 8.1% had improvement in renal function. Renal function declined by one stage in 35.2% of the cohort and by two stages in 5.4%. On analysis without chronic kidney disease staging, 24.3% of patients had latest follow-up creatinine concentration >1.5 mg/dL, 29.7% had latest follow-up creatinine concentration increase >30%, and 24.3% had latest follow-up GFR decline >30%. Mean survival time from significant renal decline was 23.4 months.sn-EVAR continues to demonstrate a high rate of technical success and results in only mild rates of acute and midterm renal function decline according to a number of established definitions for renal dysfunction. Continued monitoring of renal function, renal stent behavior, and abdominal aortic aneurysm sac changes remains critically important in the long-term management of patients undergoing sn-EVAR, particularly given the high comorbidities associated with juxtarenal aortic aneurysms.

Abstract

Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease affecting 4-8% of men older than 60 years. No pharmacologic strategies limit disease progression, aneurysm rupture, or aneurysm-related death. We examined the ability of rapamycin to limit the progression of established experimental AAAs.AAAs were created in 10-12-week-old male C57BL/6J mice via the porcine pancreatic elastase (PPE) infusion method. Beginning 4 days after PPE infusion, mice were treated with rapamycin (5 mg/kg/day) or an equal volume of vehicle for 10 days. AAA progression was monitored by serial ultrasound examination. Aortae were harvested for histological analyses at sacrifice.Three days after PPE infusion, prior to vehicle or rapamycin treatment, aneurysms were enlarging at an equal rate between groups. In the rapamycin group, treatment reduced aortic enlargement by 38%, and 53% at 3 and 10 days, respectively. On histological analysis, medial elastin and smooth muscle cell populations were relatively preserved in the rapamycin group. Rapamycin treatment also reduced mural macrophage density and neoangiogenesis.Rapamycin limits the progression of established experimental aneurysms, increasing the translational potential of mechanistic target of rapamycin-related AAA inhibition strategies.

Abstract

Screening and surveillance are recommended in the management of small abdominal aortic aneurysms (AAAs). Gaps in surveillance after early diagnosis may lead to unrecognized AAA growth, rupture, and death. This study investigates the frequency and predictors of rupture of previously diagnosed AAAs.Data were extracted from Medicare claims for patients who underwent AAA repair between 2006 and 2009. Relevant preoperative abdominal imaging exams were tabulated up to 5 years prior to AAA repair. Repair for ruptured AAAs was compared with repair for intact AAAs for those with an early diagnosis of an AAA, defined as having received imaging at least 6 months prior to surgery. Gaps in surveillance were defined as no image within 1 year of surgery or no imaging for more than a 2-year time span after the initial image. Logistic regression was used to examine independent predictors of rupture despite early diagnosis.A total of 9298 patients had repair after early diagnosis, with rupture occurring in 441 (4.7%). Those with ruptured AAAs were older (80.2 ± 6.9 vs 77.6 ± 6.2 years; P < .001), received fewer images prior to repair (5.7 ± 4.1 vs 6.5 ± 3.5; P = .001), were less likely to be treated in a high-volume hospital (45.4% vs 59.5%; P < .001), and were more likely to have had gaps in surveillance (47.4% vs 11.8%; P < .001) compared with those receiving repair for intact AAAs. After adjusting for medical comorbidities, gaps in surveillance remained the largest predictor of rupture in a multivariate analysis (odds ratio, 5.82; 95% confidence interval, 4.64-7.31; P < .001).Despite previous diagnosis of AAA, many patients experience rupture prior to repair. Improved mechanisms for surveillance are needed to prevent rupture and ensure timely repair for patients with AAAs.

Abstract

Abdominal aortic aneurysm (AAA) disease is a common, morbid, and highly lethal pathology. Extraordinary efforts have been launched to determine the molecular and pathophysiological characteristics of AAAs. Although surgery is highly effective in preventing death by rupture for larger AAAs, no guidance or preventive therapy is currently available for the >90% of patients whose aneurysms are below the surgical threshold. Predictive animal models of AAA as well as human pathological samples have revealed a complex circuit of AAA formation and progression. The proteolytic destruction of matrix components of the aorta by different proteases has been extensively studied over many years. Recently, a novel class of small noncoding RNAs, called microRNAs, was identified as "fine-tuners" of the translational output of target genes; they act by promoting mRNA degradation. Their therapeutic potential in limiting AAA development appears very intriguing. Further, current studies assessing genetic and heritable associations for AAA disease have provided great insight into its pathogenesis, potentially enabling us to better clinically manage affected patients.

Abstract

Identification and treatment of abdominal aortic aneurysm (AAA) remain among the most prominent challenges in vascular medicine. MicroRNAs (miRNAs) are crucial regulators of cardiovascular pathology and represent intriguing targets to limit AAA expansion. Here we show, by using two established murine models of AAA disease along with human aortic tissue and plasma analysis, that miR-24 is a key regulator of vascular inflammation and AAA pathology. In vivo and in vitro studies reveal chitinase 3-like 1 (Chi3l1) to be a major target and effector under the control of miR-24, regulating cytokine synthesis in macrophages as well as their survival, promoting aortic smooth muscle cell migration and cytokine production, and stimulating adhesion molecule expression in vascular endothelial cells. We further show that modulation of miR-24 alters AAA progression in animal models, and that miR-24 and CHI3L1 represent novel plasma biomarkers of AAA disease progression in humans.

Abstract

As part of a home-based rehabilitation program, 24 older adult patients (71 ± 3 years) with abdominal aortic aneurysm (AAA) disease underwent 3 days (12 awake hr/day) of activity monitoring using an accelerometer (ACC), a pedometer, and a heart rate (HR) monitor, and recorded hourly activity logs. Subjects then underwent an interview to complete a 3-day activity recall questionnaire (3-DR). Mean energy expenditure (EE) in kcals/ day for HR, ACC, and 3-DR were 1,687 ± 458, 2,068 ± 529, and 1,974 ± 491, respectively. Differences in EE were not significant between 3-DR and ACC, but HR differed from both ACC (p < .001) and 3-DR (p < .01). ACC and 3-DR had the highest agreement, with a coefficient of variation of 7.9% and r = .86. Thus, ACC provided a reasonably accurate reflection of EE based the criterion measure, an activity recall questionnaire. ACC can be effectively used to monitor EE to achieve an appropriate training stimulus during home-based cardiac rehabilitation.

Abstract

Screening programs and greater public awareness have increased the recognition of early abdominal aortic aneurysm (AAA) disease. No medical therapy has proven effective in limiting AAA progression, and little is known regarding the safety and efficacy of exercise training in these patients. We evaluated the safety and efficacy of up to 3 years of training in patients with early (≤5.5 cm) AAA disease.One hundred forty patients with small AAAs (72±8 years) were randomized to exercise training (n=72) or usual care (n=68). Exercise subjects participated in a combination of in-house and home training for up to 3 years. Cardiopulmonary exercise testing (CPX) was performed at baseline and 3, 12, 24, and 36 months. Comparisons were made for AAA expansion, safety, CPX responses, and weekly energy expenditure.Average duration of participation was 23.4 ±9.6 months; 81% of subjects completed ≥ 1 year. No adverse clinical events or excessive AAA growth rates related to training occurred. Exercise subjects expended a mean 1999±1030 kcals/week. Increases in peak exercise time and estimated METs occurred at the 3 month and 1, 2, and 3-year evaluations (p<0.01 between groups). A significant between-group interaction occurred for VO2 at the ventilatory threshold (p=0.02), and submaximal heart rate was significantly reduced among exercise subjects. Neither exercise status nor level of fitness significantly influenced rate of AAA enlargement.These results support the safety and efficacy of training in patients with small AAA, a population for which few previous data are available. Despite advanced age and co-morbidities, training up to 3 years was well tolerated and sustainable in AAA patients. Training did not influence rate of AAA enlargement.

Abstract

OBJECTIVE: Rates of inferior vena cava (IVC) filter retrieval have remained suboptimal, in part because of poor follow-up. The goal of our study was to determine demographic and clinical factors predictive of IVC filter follow-up care in a university hospital setting. METHODS: We reviewed 250 consecutive patients who received an IVC filter placement with the intention of subsequent retrieval between March 2009 and October 2010. Patient demographics, clinical factors, and physician specialty were evaluated. Multivariate logistic regression analysis was performed to identify variables predicting follow-up care. RESULTS: In our cohort, 60.7% of patients received follow-up care; of those, 93% had IVC filter retrieval. Major indications for IVC filter placement were prophylaxis for high risk surgery (53%) and venous thromboembolic event with contraindication and/or failure of anticoagulation (39%). Follow-up care was less likely for patients discharged to acute rehabilitation or skilled nursing facilities (P < .0001), those with central nervous system pathology (eg, cerebral hemorrhage or spinal fracture; P < .0001), and for those who did not receive an IVC filter placement by a vascular surgeon (P < .0001). In a multivariate analysis, discharge home (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.99-8.2; P < .0001), central nervous system pathology (OR, 0.46; 95% CI, 0.22-0.95; P = .04), and IVC filter placement by the vascular surgery service (OR, 4.7; 95% CI, 2.3-9.6; P < .0001) remained independent predictors of follow-up care. Trauma status and distance of residence did not significantly impact likelihood of patient follow-up. CONCLUSIONS: Service-dependent practice paradigms play a critical role in patient follow-up and IVC filter retrieval rates. Nevertheless, specific patient populations are more prone to having poorer rates of follow-up. Such trends should be factored into institutional quality control goals and patient-centered care.

Abstract

Treatment of abdominal aortic aneurysms with high-risk anatomy (neck length <10-15 mm, neck angle >60°) using commercially available devices has become increasingly common with expanding institutional experience. We examined whether placement of approved devices in short angled necks provides acceptable durability at early and intermediate time points.A total of 218 patients (197 men, 21 women) at a single academic center underwent endovascular aneurysm repair (EVAR) with a commercially available device between January 2004 and December 2007. Available medical records, pre- and postoperative imaging, and clinical follow-up were retrospectively reviewed. Patients were divided into those with suitable anatomy (instructions for use, IFU) for EVAR and those with high-risk anatomic aneurysm characteristics (non-IFU).IFU (n = 143) patients underwent repair with Excluder (40%), AneuRx (34%), and Zenith (26%) devices, whereas non-IFU (n = 75) were preferentially treated with Zenith (57%) over Excluder (25%) and AneuRx (17%). Demographics and medical comorbidities between the groups were similar. Operative mortality was 1.4% (2.1% IFU, 0% non-IFU) with mean follow-up of 35 months (range 12-72). Non-IFU patients tended to have larger sac diameters (46.7% ≥60 mm) with shorter (30.7% ≤10 mm), conical (49.3%), and more angled (68% >60°) necks (all p .05).EVAR may be performed safely in high-risk patients with unfavorable neck anatomy using particular commercially available endografts. In our experience, the preferential use of active suprarenal fixation and aggressive use of proximal cuffs is associated with optimal results in these settings. Mid-term outcomes are comparable with those achieved in patients with suitable anatomy using a similar range of EVAR devices. Careful and mandatory long-term follow-up will be necessary to confirm the benefit of treating these high-risk anatomic patients.

Abstract

Abdominal aortic aneurysm (AAA) screening remains largely underutilized in the U.S., and it is likely that the proportion of patients with aneurysms requiring prompt treatment is much higher compared with well-screened populations. The goals of this study were to determine the proportion of AAAs that required prompt repair after diagnostic abdominal imaging for U.S. Medicare beneficiaries and to identify patient and hospital factors contributing to early vs late diagnosis of AAA.Data were extracted from Medicare claims records for patients at least 65 years old with complete coverage for 2 years who underwent intact AAA repair from 2006 to 2009. Preoperative ultrasound and computed tomography was tabulated from 2002 to repair. We defined early diagnosis of AAA as a patient with a time interval of greater than 6 months between the first imaging examination and the index procedure, and late diagnosis as patients who underwent the index procedure within 6 months of the first imaging examination.Of 17,626 patients who underwent AAA repair, 14,948 met inclusion criteria. Mean age was 77.5 ± 6.1 years. Early diagnosis was identified for 60.6% of patients receiving AAA repair, whereas 39.4% were repaired after a late diagnosis. Early diagnosis rates increased from 2006 to 2009 (59.8% to 63.4%; P < .0001) and were more common for intact repair compared with repair after rupture (62.9% vs 35.1%; P < .0001) and for women compared with men (66.3% vs 59.0%; P < .0001). On multivariate analysis, repair of intact vs ruptured AAAs (odds ratio, 3.1; 95% confidence interval, 2.7-3.6) and female sex (odds ratio, 1.4; 95% confidence interval, 1.3-1.5) remained the strongest predictors of surveillance. Although intact repairs were more likely to be diagnosed early, over one-third of patients undergoing repair for ruptured AAAs received diagnostic abdominal imaging greater than 6 months prior to surgery.Despite advances in screening practices, significant missed opportunities remain in the U.S. Medicare population for improving AAA care. It remains common for AAAs to be diagnosed when they are already at risk for rupture. In addition, a significant proportion of patients with early imaging rupture prior to repair. Our findings suggest that improved mechanisms for observational management are needed to ensure optimal preoperative care for patients with AAAs.

Abstract

Statins are thought to reduce vascular inflammation through lipid independent mechanisms. Evaluation of such an effect in atherosclerotic disease is complicated by simultaneous effects on lipid metabolism. Abdominal aortic aneurysms (AAA) are part of the atherosclerotic spectrum of diseases. Unlike atherosclerotic occlusive disease, AAA is not lipid driven, thus allowing direct evaluation of putative anti-inflammatory effects. The anti-inflammatory potency of increasing doses (0, 20 or 40 mg/day) simvastatin or atorvastatin was evaluated in 63 patients that were at least 6 weeks on statin therapy and who underwent open AAA repair. A comprehensive analysis using immunohistochemistry, mRNA and protein analyses was applied on aortic wall samples collected during surgery. The effect of statins on AAA growth was analyzed in a separate prospective study in incorporating 142 patients. Both statins equally effectively and dose-dependently reduced aortic wall expression of NFκB regulated mediators (i.e. IL-6 (P<0.001) and MCP-1 (P<0.001)); shifted macrophage polarization towards a M2 phenotype (P<0.0003); selectively reduced macrophage-related markers such as cathepsin K and S (P<0.009 and 0.0027 respectively), and ALOX5 (P<0.0009), and reduced vascular wall NFκB activity (40 mg/day group, P<0.016). No effect was found on other cell types. Evaluation of the clinical efficacy of statins to reduce AAA progression did not indicate an effect of statins on aneurysm growth (P<0.337). Hence, in the context of AAA the clinical relevance of statins pleiotropy appears minimal.

Abstract

Genomewide association studies have implicated allelic variation at 9p21.3 in multiple forms of vascular disease, including atherosclerotic coronary heart disease and abdominal aortic aneurysm. As for other genes at 9p21.3, human expression quantitative trait locus studies have associated expression of the tumor suppressor gene CDKN2B with the risk haplotype, but its potential role in vascular pathobiology remains unclear.Here we used vascular injury models and found that Cdkn2b knockout mice displayed the expected increase in proliferation after injury, but developed reduced neointimal lesions and larger aortic aneurysms. In situ and in vitro studies suggested that these effects were attributable to increased smooth muscle cell apoptosis. Adoptive bone marrow transplant studies confirmed that the observed effects of Cdkn2b were mediated through intrinsic vascular cells and were not dependent on bone marrow-derived inflammatory cells. Mechanistic studies suggested that the observed increase in apoptosis was attributable to a reduction in MDM2 and an increase in p53 signaling, possibly due in part to compensation by other genes at the 9p21.3 locus. Dual inhibition of both Cdkn2b and p53 led to a reversal of the vascular phenotype in each model.These results suggest that reduced CDKN2B expression and increased smooth muscle cell apoptosis may be one mechanism underlying the 9p21.3 association with aneurysmal disease.

Abstract

In addition to increased risks for aneurysm-related death, previous studies have determined that all-cause mortality in abdominal aortic aneurysm (AAA) patients is excessive and equivalent to that associated with coronary heart disease. These studies largely preceded the current era of coronary heart disease risk factor management, however, and no recent study has examined contemporary mortality associated with early AAA disease (aneurysm diameter between 3 and 5 cm). As part of an ongoing natural history study of AAA, we report the mortality risk associated with presence of early disease.Participants were recruited from three distinct health care systems in Northern California between 2006 and 2011. Aneurysm diameter, demographic information, comorbidities, medication history, and plasma for biomarker analysis were collected at study entry. Survival status was determined at follow-up. Data were analyzed with t-tests or ?(2) tests where appropriate. Freedom from death was calculated via Cox proportional hazards modeling; the relevance of individual predictors on mortality was determined by log-rank test.The study enrolled 634 AAA patients; age 76.4 ± 8.0 years, aortic diameter 3.86 ± 0.7 cm. Participants were mostly male (88.8%), not current smokers (81.6%), and taking statins (76.7%). Mean follow-up was 2.1 ± 1.0 years. Estimated 1- and 3-year survival was 98.2% and 90.9%, respectively. Factors independently associated with mortality included larger aneurysm size (hazard ratio, 2.12; 95% confidence interval, 1.26-3.57 for diameter >4.0 cm) and diabetes (hazard ratio, 2.24; 95% confidence interval, 1.12-4.47). After adjusting for patient-level factors, health care system independently predicted mortality.Contemporary all-cause mortality for patients with early AAA disease is lower than that previously reported. Further research is warranted to determine important factors that contribute to improved survival in early AAA disease.

Abstract

The new integrated 0 + 5 vascular surgery (VS) training paradigm introduced in 2007 required program directors and faculty to reconsider recruiting methods and exposure of medical students to VS. As a means to identify variables important for recruitment of 0 + 5 VS applicants, we sought to analyze national 0 + 5 VS residency application trends and to compare medical school demographics of applicants to both our 0 + 5 residency and 5 + 2 fellowship programs.Electronic Residency Application Service and National Resident Matching Program online public databases were queried to evaluate nationwide trends in the number of applicants to integrated VS residency programs between 2007 and 2010. Demographic data from Electronic Residency Application Service applications submitted to our institution's 0 + 5 and 5 + 2 VS training programs during the same time period were reviewed.From 2008 to 2011, there were 190 applicants to our 0 + 5 VS residency program and 161 applicants to our 5 + 2 fellowship program, with 127 (66.8%) and 122 (75.8%) being United States medical graduates, respectively. Annual application volume to our programs over these years remained stable for both training pathways (range, 39-49 for 0 + 5 integrated; range, 39-43 for 5 + 2 traditional). Nationally, applications to 0 + 5 programs increased sixfold over the same time period (52 in 2007 to 340 applicants in 2010; P < .001), far exceeding the available training positions. Compared with applicants to the 5 + 2 VS fellowships, medical students applying to the 0 + 5 programs are more likely to be female, be slightly older, have additional postgraduate degrees and publications, have higher United States Medical Licensure Examination test scores, and are more likely to be in the top quartile of their medical school class.Nationwide interest in the 0 + 5 vascular surgery residency training paradigm continues to significantly increase. Significant differences exist between the cohorts of 0 + 5 residency and 5 + 2 fellowship program applicants at the completion of medical school, suggesting that 0 + 5 VS residency programs are attracting a different medical student population to the VS specialty. VS program directors should continue to foster interest in this new applicant pool through early exposure, mentorship, and extracurricular research activities.

Abstract

Current information regarding coverage of accessory renal arteries (ARAs) during endovascular aneurysm repair (EVAR) is based on small case series with limited follow-up. This study evaluates the outcomes of ARA coverage in a large contemporary cohort.Consecutive EVAR data from January 2004 to August 2010 were collected in a prospective database at a University Hospital. Patient and aneurysm-related characteristics, imaging studies, and ARA coverage versus preservation were analyzed. Volumetric analysis of three-dimensional reconstruction computed tomography scans was used to assess renal infarction volume extent. Long-term renal function and overall technical success of aneurysm exclusion were compared.A cohort of 426 EVARs was identified. ARAs were present in 69 patients with a mean follow-up of 27 months (range, 1 to 60 months). Forty-five ARAs were covered in 40 patients; 29 patients had intentional ARA preservation. Patient and anatomic characteristics were similar between groups except that ARA coverage patients had shorter aneurysm necks (P = .03). Renal infarctions occurred in 84% of kidneys with covered ARAs. There was no significant deterioration in long-term glomerular filtration rate when compared with patients in the control group. No difference in the rate of endoleak, secondary procedures, or the requirement for antihypertensive medications was found.This study is the largest to date with the longest follow-up relating to ARA coverage. Contrary to previous reports, renal infarction after ARA coverage is common. Nevertheless, coverage is well tolerated based upon preservation of renal function without additional morbidity. These results support the long-term safety of ARA coverage for EVAR when necessary.

Abstract

Although challenging proximal necks have limited the utility of standard endovascular aneurysm repair (EVAR) devices, sophisticated endovascular techniques have evolved in recent years for the repair of juxtarenal abdominal aortic aneurysms (AAAs). Among these techniques, snorkel or chimney EVAR (sn-EVAR) and fenestrated EVAR (f-EVAR) have emerged as options for repairing anatomic high-risk AAAs. Unfortunately, in the United States, except in the context of a clinical trial or physician-sponsored device exemption, limited long-term data exist on the treatment of juxta- and suprarenal AAAs with either sn-EVAR or f-EVAR. Owing to these limitations, comparison of these two techniques is challenging, and we sought to describe a case when one was favored over the other.A 72-year-old man presented with an enlarging, asymptomatic, juxtarenal fusiform AAA (5.9 cm), a moderately enlarged right common iliac artery (2.8 cm), a history of oxygen-dependent chronic obstructive pulmonary disease, and a previous right nephrectomy. An initial sn-EVAR was attempted but was unsuccessful owing to the inability to deliver the "snorkel" covered stent via a brachial approach because of renal ostial stenosis and cephalad angulation of the patient's left renal artery. A subsequent f-EVAR approach was successfully used to repair the juxtarenal AAA while preserving adequate renal artery blood flow. Two-year postoperative follow-up demonstrated a stable endovascular repair without endoleaks, a shrinking aneurysm sac, and stable renal function.The sn-EVAR configuration in this case report was precluded by cephalad renal angulation, and the AAA was instead repaired using an f-EVAR approach, with good 2-year follow-up outcomes. The sn-EVAR strategy requires downward pointing renal arteries in addition to adequate brachial/axillary artery access dimensions to facilitate successful repair. With improving techniques and technology for either approach, anatomic specifications and indications for these advanced EVAR strategies will need to be delineated.

Abstract

Endovascular aneurysm repair (EVAR) in women is often technically limited by smaller access vessel anatomy, particularly at the femoral and iliac artery levels. Percutaneous femoral artery access and closure using the "Preclose" technique (PERC) is a less invasive alternative to open surgical femoral arterial exposure and has been reported to be technically feasible, particularly in male cohorts. The purpose of this study was to evaluate the efficacy and access-related outcomes of PERC in women undergoing EVAR.We identified female patients in a prospectively maintained EVAR database from 2000 to 2009. An all-percutaneous approach was adopted in 2007 if technically feasible, based on preoperative computed tomography angiogram criteria including a femoral diameter >7 mm, <25% posterior plaque and lack of circumferential calcification/disease. All percutaneous EVAR procedures were performed using two Perclose Proglide devices in a standardized manner for sheath sizes ranging between 12F and 26F.In period 1 (2000-2006), most cases were performed with open femoral exposure. In period 2 (2007-2009), our group adopted a percutaneous-first approach. Of 736 EVARs performed during the study period, 120 (16.3%) were in women, leading to 178 femoral arteries requiring large sheath access. Period 1 included 90 women and period 2 included 30 women who were evaluated for percutaneous access. During period 2, of the 47 eligible femoral arteries for possible PERC, 24 (51%) met appropriate criteria, and the Preclose technique was employed. The remaining 23 femoral arteries during period 2 were accessed with surgical exposure (OPEN). Technical success rate of PERC in period 2 was 96%, with one device pulling through a thin anterior arterial wall requiring open femoral conversion. During period 2, the OPEN cohort had a higher rate of total wound complications compared with PERC (34.8% vs. 8.3%, P = 0.02), including hematomas (8.7% vs. 0%), wound breakdowns (8.7% vs. 0%), and pseudoaneurysms (4.3% vs. 0%). There were two cases of femoral artery thrombosis in the PERC group requiring repair in the immediate postoperative period; however, this was not significantly different compared with the OPEN group (8.7% vs. 8.3%).Selective percutaneous access of the femoral arteries for EVAR is safe and effective in the female population, with fewer wound complications than open exposure. Approximately one-half of femoral arteries in women are eligible for PERC access, and complications can be limited with careful selection based on preoperative imaging.

Abstract

The lack of readily available branched and fenestrated endovascular aneurysm repair (EVAR) options has created an opportunity for creative deployment of endograft components to treat juxtarenal aneurysms. We present our early experience with "snorkel" or "chimney" techniques in the endovascular management of complex aortic aneurysms.We retrospectively reviewed planned snorkel procedures for juxtarenal aneurysms performed from September 2009 to August 2011. Our standardized technique included axillary or brachial cutdown for delivery of covered snorkel stents and mostly percutaneous femoral access for the main body endograft.Fifty-six snorkel grafts were successfully placed in 28 consecutive patients (mean age, 75 years) with juxtarenal aneurysms. Mean aneurysm size was 64.8 mm (range, 53-87 mm). The snorkel configuration extended the proximal seal zone from an unsuitable infrarenal neck for standard EVAR (median diameter, 33.5 mm; length, 0.0 mm) to a median neck diameter of 24.5 mm and length of 18.0 mm. Five patients had unilateral renal snorkels, 17 had bilateral renal snorkels, and six had celiac/superior mesenteric artery/renal combinations. Technical success of snorkel placements was 98.2%, with loss of wire access leading to one renal stent deployment failure. Thirty-day mortality was 7.1%: one patient was readmitted 1 week postoperatively with pneumonia and died of sepsis; one patient died at 1 week of a right hemispheric stroke. Other major complications included perinephric hematomas, 7.1%; permanent hemodialysis, 3.6%; iliac artery injury requiring endoconduit placement, 3.6%; and brachial plexus nerve injury, 3.6%. Cardiac complications included self-limited arrhythmias (14.3%) and one non-Q-wave myocardial infarction (3.6%), with all recovering without coronary intervention. Mean follow-up was 10.7 months (range, 3-25 months). One patient died of nonaneurysmal-related causes at 3 months (89.3% survival). Postoperative imaging revealed one renal snorkel graft occlusion occurring at 3 months (98.2% overall primary patency). Seven (25%) early endoleaks were noted on the first follow-up computed tomography angiography: two type I, three type II, and two type III (25%), leading to one secondary intervention (3.6%) with bridging cuff placement (type III). The small type Ia endoleaks and other type III endoleak resolved at the 6-month scan. Mean sac regression at the latest follow-up was 7.3 mm. No aneurysm has enlarged on postoperative imaging.Early success with the snorkel technique for juxtarenal aneurysms has made it our procedure of choice for complex short-neck to no-neck EVAR. Although long-term follow-up is needed, the flexibility of the snorkel technique and lack of requirement for custom-built devices may make this approach more attractive than branched or fenestrated stent grafts.

Abstract

Macrophage infiltration is a prominent feature of abdominal aortic aneurysm (AAA) progression. We used a combined imaging approach with bioluminescence (BLI) and magnetic resonance imaging (MRI) to study macrophage homing and accumulation in experimental AAA disease. Murine AAAs were created via intra-aortic infusion of porcine pancreatic elastase. Mice were imaged over 14 days after injection of prepared peritoneal macrophages. For BLI, macrophages were from transgenic mice expressing luciferase. For MRI, macrophages were labeled with iron oxide particles. Macrophage accumulation during aneurysm progression was observed by in situ BLI and by in vivo 7T MRI. Mice were sacrificed after imaging for histologic analysis. In situ BLI (n ?=? 32) demonstrated high signal in the AAA by days 7 and 14, which correlated significantly with macrophage number and aortic diameter. In vivo 7T MRI (n ?=? 13) at day 14 demonstrated T?* signal loss in the AAA and not in sham mice. Immunohistochemistry and Prussian blue staining confirmed the presence of injected macrophages in the AAA. BLI and MRI provide complementary approaches to track macrophage homing and accumulation in experimental AAAs. Similar dual imaging strategies may aid the study of AAA biology and the evaluation of novel therapies.

Abstract

Identification and treatment of abdominal aortic aneurysm (AAA) remains among the most prominent challenges in vascular medicine. MicroRNAs are crucial regulators of cardiovascular pathology and represent possible targets for the inhibition of AAA expansion. We identified microRNA-21 (miR-21) as a key modulator of proliferation and apoptosis of vascular wall smooth muscle cells during development of AAA in two established murine models. In both models (AAA induced by porcine pancreatic elastase or infusion of angiotensin II), miR-21 expression increased as AAA developed. Lentiviral overexpression of miR-21 induced cell proliferation and decreased apoptosis in the aortic wall, with protective effects on aneurysm expansion. miR-21 overexpression substantially decreased expression of the phosphatase and tensin homolog (PTEN) protein, leading to increased phosphorylation and activation of AKT, a component of a pro-proliferative and antiapoptotic pathway. Systemic injection of a locked nucleic acid-modified antagomir targeting miR-21 diminished the pro-proliferative impact of down-regulated PTEN, leading to a marked increase in the size of AAA. Similar results were seen in mice with AAA augmented by nicotine and in human aortic tissue samples from patients undergoing surgical repair of AAA (with more pronounced effects observed in smokers). Modulation of miR-21 expression shows potential as a new therapeutic option to limit AAA expansion and vascular disease progression.

Abstract

MicroRNAs (miRs) regulate gene expression at the posttranscriptional level and play crucial roles in vascular integrity. As such, they may have a role in modifying abdominal aortic aneurysm (AAA) expansion, the pathophysiological mechanisms of which remain incompletely explored. Here, we investigate the role of miRs in 2 murine models of experimental AAA: the porcine pancreatic elastase (PPE) infusion model in C57BL/6 mice and the AngII infusion model in Apoe-/- mice. AAA development was accompanied by decreased aortic expression of miR-29b, along with increased expression of known miR-29b targets, Col1a1, Col3a1, Col5a1, and Eln, in both models. In vivo administration of locked nucleic acid anti-miR-29b greatly increased collagen expression, leading to an early fibrotic response in the abdominal aortic wall and resulting in a significant reduction in AAA progression over time in both models. In contrast, overexpression of miR-29b using a lentiviral vector led to augmented AAA expansion and significant increase of aortic rupture rate. Cell culture studies identified aortic fibroblasts as the likely vascular cell type mediating the profibrotic effects of miR-29b modulation. A similar pattern of reduced miR-29b expression and increased target gene expression was observed in human AAA tissue samples compared with that in organ donor controls. These data suggest that therapeutic manipulation of miR-29b and its target genes holds promise for limiting AAA disease progression and protecting from rupture.

Abstract

Modular stent-graft systems for endovascular aneurysm repair (EVAR) most often require two to three components, depending on the device. Differences in path lengths and availability of main body systems often require additional extensions for appropriate aneurysm exclusion. These additional devices usually result in added expenses and can affect the financial viability of an EVAR program within a hospital. The purpose of this study was to analyze the use of extensions during EVAR, focusing on incidence, clinical impact, and financial impact, as well as determining the associated cost differences between two- and three-component EVAR device systems.We reviewed available clinical data, images, and follow-up of 218 patients (203 males and 15 females, mean age: 74 ± 9 years) who underwent elective EVAR at a single academic center from 2004 to 2007. Patients were divided into two groups: patients undergoing EVAR using the standard number of pieces, that is, no extensions used (group A, n = 98), and those needing proximal or distal extensions during the index procedure (group B, n = 120).Both groups were similar in terms of demographics; preoperative characteristics, including aneurysm morphology; as well as intraoperative, postoperative, and midterm outcomes. Overall, 30-day operative mortality was 1.4%, with a mean follow-up of 24 months. Group A patients underwent repair with two-piece modular devices 41% of the time and three-piece systems 59% of the time, whereas group B patients underwent repair with two-piece modular systems 82% of the time and three-piece modular systems 18% of the time. The number of additional extensions per patient ranged from one to four (median: one piece). There was a 30% cost increase in overall mean device-related cost when using extensions versus the standard number of pieces (group A: $13,220 vs. group B: $17,107, p < 0.01).Clinical midterm aneurysm-related outcomes after EVAR in patients who required additional extensions was comparable with those treated with the standard number of pieces. An increased number of extensions led to increased costs and could have potentially been minimized with appropriate preoperative planning or device selection. Consideration should be made toward per-case pricing instead of per-piece pricing to further improve cost efficiency without compromising long-term patient outcomes.

Abstract

Loeys-Dietz syndrome (LDS) is a rare congenital connective tissue disorder (CTD) caused by mutations in the gene encoding for transforming growth factor-? receptors I and II. This recently described syndrome is characterized by aortic aneurysms and dissections, arterial tortuosity, and spontaneous organ perforation. The technical feasibility of endovascular interventions, particularly endovascular aneurysm repair (EVAR), in CTDs is relatively unknown.A 38-year-old man presented with asymptomatic bilateral common iliac artery aneurysms measuring 5.3 cm on the right and 4.3 cm on the left. The patient had an extensive surgical and medical history, including a recently repaired Stanford type-A aortic dissection, total colectomy with end ileostomy for a colonic perforation, splenectomy for rupture, and cirrhosis secondary to chronic hepatitis C. The patient's CTD, multiple abdominal surgeries performed in the past, and ileostomy made him a poor candidate for open repair. We elected to offer him a complex endovascular repair and hoped to preserve his pelvic circulation by using "double-barrel" configuration of stent-grafts in the right iliac artery system. Successful deployment of the devices and repair of femoral access allowed routine discharge on postoperative day 2. At 6-month follow-up, the patient's pelvic circulation has been maintained, the aneurysms are excluded without endoleak, and sac regression has been shown.LDS is a rare connective tissue disorder characterized by vascular aneurysms and arterial tortuosity. When vascular reconstruction is necessary, open techniques are often preferred given the lack of data on endovascular procedures. In the present case, we report the first successful abdominal EVAR in a high-risk patient with LDS, providing excellent short-term results.

Abstract

Surging interest in the 0 + 5 integrated vascular surgery (VS) residency and successful recruitment of the top students in medical school requires early exposure to the field. We sought to determine the impact of a high-fidelity simulation-based preclinical endovascular skills course on medical student performance and ultimate career specialty choices.Fifty-two preclinical medical students enrolled in an 8-week VS elective course from 2007 to 2009. Students completed a baseline and postcourse survey and performed a renal angioplasty/stent procedure on an endovascular simulator (pretest). A curriculum consisting of didactic teaching covering peripheral vascular disease and weekly mentored simulator sessions concluded with a final graded procedure (posttest). Long-term follow-up surveys 1 to 3 years after course completion were administered to determine ultimate career paths of participants as well as motivating factors for career choice.Objective and subjective performance measured on the simulator and through structured global assessment scales improved in all students from pre- to posttest, particularly with regard to technical skill and overall procedural competency (P < .001). Prior to enrolling in the course, 9% of the students expressed high interest in VS, and after completing the course, this response nearly tripled in terms of seriously considering VS as a career option (P = .03). Overall interest postcourse in VS and procedural-based surgical specialties was nearly 90%. In long-term follow-up, 25% were still strongly considering integrated VS residencies, with other top career choices including surgical subspecialties (64%), radiology (10%), and cardiology (6%). Most respondents indicated major reasons for continued interest in VS were the ability to practice endovascular procedures on the simulator (92%) and mentorship from VS faculty (70%).Basic endovascular skills can be efficiently introduced through a simulation-based curriculum and lead to improved novice performance. Early exposure of preclinical medical students provides an effective teaching and recruitment tool for procedural-based fields, particularly surgical subspecialties. Mentored exposure to endovascular procedures on the simulator positively impacts long-term medical student attitudes toward vascular surgery and ultimate career choices.

Abstract

Abdominal aortic aneurysm (AAA) is a vascular disease resulting in a permanent, localized enlargement of the abdominal aorta. We previously hypothesized that the progression of AAA may be slowed by altering the hemodynamics in the abdominal aorta through exercise [Dalman, R. L., M. M. Tedesco, J. Myers, and C. A. Taylor. Ann. N.Y. Acad. Sci. 1085:92-109, 2006]. To quantify the effect of exercise intensity on hemodynamic conditions in 10 AAA subjects at rest and during mild and moderate intensities of lower-limb exercise (defined as 33 ± 10% and 63 ± 18% increase above resting heart rate, respectively), we used magnetic resonance imaging and computational fluid dynamics techniques. Subject-specific models were constructed from magnetic resonance angiography data and physiologic boundary conditions were derived from measurements made during dynamic exercise. We measured the abdominal aortic blood flow at rest and during exercise, and quantified mean wall shear stress (MWSS), oscillatory shear index (OSI), and particle residence time (PRT). We observed that an increase in the level of activity correlated with an increase of MWSS and a decrease of OSI at three locations in the abdominal aorta, and these changes were most significant below the renal arteries. As the level of activity increased, PRT in the aneurysm was significantly decreased: 50% of particles were cleared out of AAAs within 1.36 ± 0.43, 0.34 ± 0.10, and 0.22 ± 0.06 s at rest, mild exercise, and moderate exercise levels, respectively. Most of the reduction of PRT occurred from rest to the mild exercise level, suggesting that mild exercise may be sufficient to reduce flow stasis in AAAs.

Abstract

Few data are available regarding exercise testing in patients with abdominal aortic aneurysm (AAA) disease. The purpose of this study was to evaluate safety and to characterize the hemodynamic and cardiopulmonary (CPX) response to exercise in a large group of patients with AAA.Three hundred and six patients with AAA ?3.0 to ?5.0?cm (mean 72?±?8?years) underwent CPX as part of a randomized trial of exercise training. CPX and hemodynamic responses, ischemic events, rhythm disturbances, and risk estimates based on treadmill scores were quantified and compared to an age-matched group of 2155 veterans referred for exercise testing for clinical reasons.Peak VO(2) was similar between patients with AAA and the referral group (20.0?±?6?ml/kg/min; 77 percent of age-predicted and 20.3?±?7?ml/kg/min; 80 percent of age-predicted, respectively). The incidence of exercise-induced hypotension and hypertension was higher in AAA patients versus the referral group (2.9 and 3.6 percent vs <1.0 percent, p?0.001), but there were no occurrences of ventricular tachycardia (?3 beats) or other serious events in the AAA subjects. The Duke Treadmill Score and VA Treadmill Scores, which estimate annual cardiovascular events and all-cause mortality, respectively, were similar between groups.Patients with AAA have a slightly higher incidence of hyper- and hypotensive responses to exercise than age-matched referrals, but no serious events related to CPX occurred. AAA patients can undergo maximal CPX safely and have risk scores based on treadmill test results that are similar to age-matched referral subjects. These findings extend recent studies using sub-maximal evaluations to stratify risk in patients considered for surgery, and support the routine use of exercise testing for risk evaluation and the functional assessment of patients with AAA.

Abstract

To quantitatively compare aortic curvature and motion with resulting aneurysm location, direction of expansion, and pathophysiological features in experimental abdominal aortic aneurysms (AAAs).MRI was performed at 4.7 T with the following parameters: (1) 3D acquisition for vessel geometry and (2) 2D cardiac-gated acquisition to quantify luminal motion. Male 24-week-old mice were imaged before and after AAA formation induced by angiotensin II (AngII)-filled osmotic pump implantation or infusion of elastase. AngII-induced AAAs formed near the location of maximum abdominal aortic curvature, and the leftward direction of expansion was correlated with the direction of suprarenal aortic motion. Elastase-induced AAAs formed in a region of low vessel curvature and had no repeatable direction of expansion. AngII significantly increased mean blood pressure (22.7 mm Hg, P<0.05), whereas both models showed a significant 2-fold decrease in aortic cyclic strain (P<0.05). Differences in patterns of elastin degradation and localization of fluorescent signal from protease-activated probes were also observed.The direction of AngII aneurysm expansion correlated with the direction of motion, medial elastin dissection, and adventitial remodeling. Anterior infrarenal aortic motion correlated with medial elastin degradation in elastase-induced aneurysms. Results from both models suggest a relationship between aneurysm pathological features and aortic geometry and motion.

Abstract

Hemodynamic conditions are hypothesized to affect the initiation, growth, and rupture of abdominal aortic aneurysms (AAAs), a vascular disease characterized by progressive wall degradation and enlargement of the abdominal aorta. This study aims to use magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) to quantify flow stagnation and recirculation in eight AAAs by computing particle residence time (PRT). Specifically, we used gadolinium-enhanced MR angiography to obtain images of the vessel lumens, which were used to generate subject-specific models. We also used phase-contrast MRI to measure blood flow at supraceliac and infrarenal locations to prescribe physiologic boundary conditions. CFD was used to simulate pulsatile flow, and PRT, particle residence index, and particle half-life of PRT in the aneurysms were computed. We observed significant regional differences of PRT in the aneurysms with localized patterns that differed depending on aneurysm geometry and infrarenal flow. A bulbous aneurysm with the lowest mean infrarenal flow demonstrated the slowest particle clearance. In addition, improvements in particle clearance were observed with increase of mean infrarenal flow. We postulate that augmentation of mean infrarenal flow during exercise may reduce chronic flow stasis that may influence mural thrombus burden, degradation of the vessel wall, and aneurysm growth.

Abstract

The aim of this study was to definitively assess the validity of noninvasive high-frequency ultrasound (US) measurements of aortic luminal diameter (ALD) in a murine model of elastase-induced abdominal aortic aneurysm in comparison with in situ video microscopy (VM).C57BL/6 mice underwent transient perfusion of the aorta with either elastase (n = 20: Elastase group) or saline (n = 10: Sham). Unoperated mice (n = 10) were also studied.ALD measurements by US had excellent linear correlation and absolute agreement with that by VM in both Control (unoperated or sham-operated mice) and elastase groups (r = 0.96, intraclass correlation coefficient (ICC) = 0.88 and r = 0.93, ICC = 0.92, resp.). Bland-Altman analysis of US compared with VM measurements in both groups indicated good agreement, however US measurements were slightly but significantly higher than VM measurements in the control group (mean bias 0.039?mm, P < .05). Linear regression analysis revealed excellent correlation between US and VM measurements in both groups. (R² = 0.91 in Control group, R² = 0.85 in elastase group.) The reliability of US measurements was also confirmed by ex vivo histological measurements.High-frequency US provides reliable ALD measurements in developing murine abdominal aortic aneurysms.

Abstract

To develop methods to quantify cyclic strain, motion, and curvature of the murine abdominal aorta in vivo.C57BL/6J and apoE(-/-) mice underwent three-dimensional (3D) time-of-flight MR angiography to position cardiac-gated 2D slices at four locations along the abdominal aorta where circumferential cyclic strain and lumen centroid motion were calculated. From the 3D data, a centerline through the aorta was created to quantify geometric curvature at 0.1-mm intervals. Medial elastin content was quantified with histology postmortem. The location and shape of abdominal aortic aneurysms (AAAs), created from angiotensin II infusion, were evaluated qualitatively.Strain waveforms were similar at all locations and between groups. Centroid motion was significantly larger and more leftward above the renal vessels than below (P < 0.05). Maximum geometric curvature occurred slightly proximal to the right renal artery. Elastin content was similar around the circumference of the vessel. AAAs developed in the same location as the maximum curvature and grew in the same direction as vessel curvature and motion.The methods presented provide temporally and spatially resolved data quantifying murine aortic motion and curvature in vivo. This noninvasive methodology will allow serial quantification of how these parameters influence the location and direction of AAA growth.

Abstract

"Atherosclerotic" abdominal aortic aneurysms (AAAs) occur with the greatest frequency in the distal aorta. The unique hemodynamic environment of this area predisposes it to site-specific degenerative changes. In this review, we summarize the differential hemodynamic influences present along the length of the abdominal aorta, and demonstrate how alterations in aortic flow and wall shear stress modify AAA progression in experimental models. Improved understanding of aortic hemodynamic risk profiles provides an opportunity to modify patient activity patterns to minimize the risk of aneurysmal degeneration.

Abstract

Mycotic aneurysms of the extracranial carotid artery are rare and warrant surgical intervention. Management involves open and endovascular approaches. We report the case of a 67-year-old woman with an Escherichia coli soft-tissue infection of the right retropharyngeal space and subsequent mycotic carotid aneurysm and thrombosis of the internal jugular vein. The patient presented with a pulsatile mass and right middle cerebral artery stroke. Our surgical management involved coil embolization of the aneurysm to provide for vascular control, with resection of the common carotid artery, internal carotid artery, and extracranial carotid artery branches, along with the internal jugular vein.

Abstract

Abdominal aortic aneurysms (AAAs) affect 5-7% of older Americans. We hypothesize that exercise may slow AAA growth by decreasing inflammatory burden, peripheral resistance, and adverse hemodynamic conditions such as low, oscillatory shear stress. In this study, we use magnetic resonance imaging and computational fluid dynamics to describe hemodynamics in eight AAAs during rest and exercise using patient-specific geometric models, flow waveforms, and pressures as well as appropriately resolved finite-element meshes. We report mean wall shear stress (MWSS) and oscillatory shear index (OSI) at four aortic locations (supraceliac, infrarenal, mid-aneurysm, and suprabifurcation) and turbulent kinetic energy over the entire computational domain on meshes containing more than an order of magnitude more elements than previously reported results (mean: 9.0-million elements; SD: 2.3 M; range: 5.7-12.0 M). MWSS was lowest in the aneurysm during rest 2.5 dyn/cm(2) (SD: 2.1; range: 0.9-6.5), and MWSS increased and OSI decreased at all four locations during exercise. Mild turbulence existed at rest, while moderate aneurysmal turbulence was present during exercise. During both rest and exercise, aortic turbulence was virtually zero superior to the AAA for seven out of eight patients. We postulate that the increased MWSS, decreased OSI, and moderate turbulence present during exercise may attenuate AAA growth.

Abstract

The 0 + 5 integrated vascular surgery (VS) residency has altered the training paradigm for future vascular specialists. Rising interest in these novel programs highlights our need to better understand the applicant pool. We compared demographics and surveyed recent applicants to our integrated program to gain more insight into their background and motivation for accelerated vascular training.Demographics and objective parameters were determined from all 65 applicants to the integrated VS program at Stanford University Medical Center and compared to 58 applicants interviewed by the general surgery (GS) program at Harbor-UCLA Medical Center by querying the Electronic Residency Application System for the programs in 2009. There was no overlap of applicants between programs. An anonymous, voluntary Web-based survey was sent to these cohorts with a response rate of 82% for VS applicants and 60% for GS applicants. Subjects were queried regarding their background, personal experience, prior exposure to VS, and motivations for residency specialty selection.Applicants to integrated VS programs tended to be older, were less likely to be from a US medical school, had a higher number of publications, and a higher percentage of cardiovascular-related publications than the GS applicants. When stratified by the 27 VS applicants (41%) that were offered an interview, this highly selected and desirable group for training was nearly 40% female, more likely to have an additional degree (PhD, master's), just as likely to be in the top quartile of their medical school class (60%), and score equally well on standardized board examinations (90th percentile) than the top GS applicants offered interviews. Survey data revealed that the majority of career choices (65%) were made during the third and fourth years of medical school. Factors most strongly influencing the decision to choose VS as a career were endovascular technologies/devices, challenging open vascular operations, clinical rotations on vascular surgery, the aging patient population, and perceived need for vascular surgeons and vascular surgeon mentorship. The most common reasons cited for particularly pursuing an integrated 0 + 5 VS training program were (1) more focused training/integration of cardiovascular medicine, (2) interest in catheter-based endovascular therapies, and (3) shorter time in training. Of the GS applicants, 58% indicated they would be interested in applying to an integrated residency in their subspecialty of interest, and 45% listed vascular surgery as a potential fellowship option after general surgery.Applicants to 0 + 5 integrated vascular residencies were more likely to have rotated on a vascular surgery service, observed vascular cases, identified a vascular surgery mentor, and been actively involved in cardiovascular research. The quality of the top VS applicant based on class rank and test scores is comparable to the top GS applicants, yet the VS applicant has a higher percentage of advanced degrees, more publications, and more involvement in cardiovascular research. Institutional strategies to increase medical student exposure to vascular surgery clinically and via research programs will optimize our ability to attract and train the best candidates in these new training programs.

Abstract

New training paradigms in vascular surgery allow for early specialization out of medical school. Surgical simulation has emerged as an educational tool for trainees to practice procedures in a controlled environment allowing interested medical students to perform procedures without compromising patient safety. The purpose of this study is to assess the ability of a simulation-based curriculum to improve the technical performance and interest level of medical students in vascular surgery.Prospective observational cohort study of medical student performance.Academic medical center.Forty-one medical students (23 first year, 15 second year, 3 other) enrolled in a vascular surgery elective course. Students completed a survey of their interests and performed a renal stent procedure on an endovascular simulator (pretest). The curriculum consisted of didactic teaching and weekly mentored simulator sessions and concluded with a final renal stent procedure on the simulator (posttest). Objective procedural measures were determined during the pre- and posttest by the simulator, and subjective performance was graded by expert observers utilizing a structured global assessment scale. After the course, the students were surveyed as to their opinions about vascular surgery as a career option. Finally, 1 year after the course, all students were again surveyed to determine continued interest in vascular surgery.The objective and subjective criteria measured on the simulator and structured global assessment scale significantly improved from pre- to posttest in terms of performer technical skill, patient safety measures, and structured global assessments. Before beginning the course, 8.5% of the students expressed high interest in vascular surgery, and after completing the course 70% were seriously considering vascular surgery as a career option (p = 0.0001). More than 95% of the students responded that endovascular simulation increased their knowledge and interest in vascular surgery. In the 1-year follow-up survey (n = 23 medical students), 35% had already entered their clinical years. Seventy percent of the students were still considering vascular surgery, while several other career options were still popular including the surgical subspecialties (70%), interventional cardiology (57%), and interventional radiology (48%). Most respondents indicated the major reasons for continued interest in vascular surgery were the ability to practice endovascular procedures on the simulator (100%) and mentorship from vascular surgery faculty (78%).The use of high fidelity endovascular simulation within an introductory vascular surgery course improves medical student performance with respect to technical skill, patient safety parameters, and global performance assessment. Mentored exposure to endovascular procedures on the simulator positively impacts long term medical student attitudes towards vascular surgery. Simulator-based courses may have the potential to be an important component in the assessment and recruitment of medical students for future surgical training programs.

Abstract

The introduction of ultrasound screening combined with the increasingly elderly population means that the number of small abdominal aortic aneurysms (AAAs) detected is expected to increase over the next decade. At present open or endovascular surgery are the only treatment options for AAA. In this mini-review we discuss the rationale and on-going attempts to develop non-surgical therapies for AAA.

Abstract

We have previously demonstrated a 70% incidence of microemboli on diffusion weighted magnetic resonance imaging (DW-MRI) following carotid angioplasty and stenting (CAS). The purpose of this study is to compare the incidence of microemboli in two distinct time periods when procedural modifications were implemented into a CAS program.Following a retrospective quality review of our CAS cohort (n = 27) from November 2004 through April 2006 (period 1), we enrolled patients (n = 20) from May 2006 through February 2008 (period 2) undergoing CAS into a prospective cohort that included obtaining pre- and postprocedure DW-MRI exams. Procedural modifications during period 2 included the preferential use of closed-cell systems (60% vs 0% in period 1), early heparinization at the initiation of arterial access, and elimination of an arch angiogram. The hospital records of these 47 patients were reviewed; symptoms, comorbidities, lesion characteristics, periprocedural information, and postoperative outcomes were collected. The incidence and location of acute, postprocedural microemboli were determined using DW-MRIs.Twenty (74%) CAS patients from period 1 and seven (35%) patients from period 2 demonstrated acute microemboli on postprocedural DW-MRI (P = .02). The mean number of microemboli in period 1 was 4.1 +/- 5.3 vs 1.5 +/- 2.7 during period 2 (P = .04). Two of the 27 patients (7.4%) during period 1 experienced temporary neurologic changes that resolved within 36 hours. None of the patients during period 2 exhibited any neurologic changes. Patient demographics, comorbidities, and presenting symptoms were similar between the two groups except for smoking prevalence, female presence, and obesity (BMI > 30). Period 2 patients when compared with period 1 had more technically challenging anatomy with more calcified lesions (68% vs 27%), longer lesions (15.9 mm vs 8.2 mm), and higher incidence of ulceration (55% vs 27%) (all P < .04).Despite successful performance of 47 consecutive CAS procedures without permanent neurologic sequelae, significant reductions in periprocedural embolic events as identified via DW-MRI lesions may be achieved through implementation of quality improvement measures identified through continuous outcome analysis. The long-term neurologic benefits associated with reduced subclinical neurologic events remains to be determined.

Abstract

Transient intraluminal infusion of porcine pancreatic elastase into the infrarenal segment of the abdominal aorta is the most widely used animal model of abdominal aortic aneurysm (AAA) ever since it was first described in rats by Anidjar and colleagues.(1) The rationale for its development was based on the disrupted nature of elastin observed in AAAs. This rat model has been modified to produce AAAs in the infrarenal aortic region of mice.(2) The model has the ability to add broad insight into the pathobiology of AAA due to the emergence of numerous transgenic and gene knockout mice. Moreover, it is a viable platform to test potential therapeutic agents for AAA. In this video, we demonstrate the elastase infusion AAA procedure used in our laboratory. Mice are anesthetized using 2.5% isoflurane, and a laparotomy is performed under sterile conditions. The abdominal aortais isolated with the assistance of an operating stereomicroscope (Leica). After placing temporary ligatures around the proximal and distal aorta, an aortotomy is created at the bifurcation with the tip of a 30-gauge needle. A heat-tapered segment of PE-10 polyethylene tubing is introduced through the aortotomy and secured. The aortic lumen is subsequently perfused for 5-15 minutes at 100 mm Hg with saline containing type I porcine pancreatic elastase (4.5 U/mL; Sigma Chemical Co.). After removing the perfusion catheter, the aortotomy is repaired without constriction of the lumen.

Abstract

Excess iron has been implicated in cancer risk through increased iron-catalyzed free radical-mediated oxidative stress.A multicenter randomized, controlled, single-blinded clinical trial (VA Cooperative Study #410) tested the hypothesis that reducing iron stores by phlebotomy would influence vascular outcomes in patients with peripheral arterial disease. Patients without a visceral malignancy in the last 5 years (n = 1277) were randomly assigned to control (n = 641) or iron reduction (n = 636). Occurrence of new visceral malignancy and cause-specific mortality data were collected prospectively. Cancer and mortality outcomes in the two arms were compared using intent-to-treat analysis with a Cox proportional hazards regression model. Statistical tests were two-sided.Patients were followed up for an average of 4.5 years. Ferritin levels were similar in both groups at baseline but were lower in iron reduction patients than control patients across all 6-month visits (mean = 79.7 ng/mL, 95% confidence interval [CI] = 73.8 to 85.5 ng/mL vs 122.5 ng/mL, 95% CI = 115.5 to 129.5 ng/mL; P < .001). Risk of new visceral malignancy was lower in the iron reduction group than in the control group (38 vs 60, hazard ratio [HR] = 0.65, 95% CI = 0.43 to 0.97; P = .036), and, among patients with new cancers, those in the iron reduction group had lower cancer-specific and all-cause mortality (HR = 0.39, 95% CI = 0.21 to 0.72; P = .003; and HR = 0.49, 95% CI = 0.29 to 0.83; P = .009, respectively) than those in the control group. Mean ferritin levels across all 6-monthly visits were similar in patients in the iron reduction and control groups who developed cancer but were lower among all patients who did not develop cancer than among those who did (76.4 ng/mL, 95% CI = 71.4 to 81.4 ng/mL, vs 127.1 ng/mL, 95% CI = 71.2 to 183.0 ng/mL; P = .017).Iron reduction was associated with lower cancer risk and mortality. Further studies are needed to define the role of body iron in cancer risk.

Abstract

Simulator-based endovascular skills training measurably improves performance in catheter-based image-guided interventions. The purpose of this study was to determine whether structured global performance assessment during endovascular simulation correlated well with trainee-reported procedural skill and prior experience level.Fourth-year and fifth-year general surgery residents interviewing for vascular fellowship training provided detailed information regarding prior open vascular and endovascular operative experience. The pretest questionnaire responses were used to separate subjects into low (<20 cases) and moderate (20 to 100) endovascular experience groups. Subjects were then asked to perform a renal angioplasty/stent procedure on the Procedicus Vascular Intervention System Trainer (VIST) endovascular simulator (Mentice Corporation, Gothenburg, Sweden). The subjects' performance was supervised and evaluated by a blinded expert interventionalist using a structured global assessment scale based on angiography setup, target vessel catheterization, and the interventional procedure. Objective measures determined by the simulator were also collected for each subject. A postsimulation questionnaire was administered to determine the subjects' self-assessment of their performance.Seventeen surgical residents from 15 training programs completed questionnaires before and after the exercise and performed a renal angioplasty/stent procedure on the endovascular simulator. The beginner group (n = 8) reported prior experience of a median of eight endovascular cases (interquartile range [IQR], 6.5-17.8; range, 4-20), and intermediate group (n = 9) had previously completed a median of 42 cases (IQR, 31-44; range, 25-89, P = .01). The two groups had similar prior open vascular experience (79 cases vs 75, P = .60). The mean score on the structured global assessment scale for the low experience group was 2.68 of 5.0 possible compared with 3.60 for the intermediate group (P = .03). Scores for subcategories of the global assessment score for target vessel catheterization (P = .02) and the interventional procedure (P = .05) contributed more to the differentiation between the two experience groups. Total procedure time, fluoroscopy time, average contrast used, percentage of lesion covered by the stent, placement accuracy, residual stenosis rates, and number of cine loops utilized were similar between the two groups (P > .05).Structured endovascular skills assessment correlates well with prior procedural experience within a high-fidelity simulation environment. In addition to improving endovascular training, simulators may prove useful in determining procedural competency and credentialing standards for endovascular surgeons.

Abstract

Abdominal aortic aneurysm is a common condition that may be lethal when it is unrecognized. Current guidelines suggest repair as the aneurysm diameter reaches 5.0 to 5.5 cm. Most aortic aneurysms are detected incidentally when imaging is done for other purposes or through screening programs. Ninety percent of these aneurysms are below the threshold for intervention at the time of detection. A number of studies have sought to determine factors that lead to progression of aneurysmal disease that might be amenable to intervention during this period of observation. We review these studies and make recommendations for the medical management of small abdominal aortic aneurysms. On the basis of our current knowledge of the causes of aneurysm, a number of approaches have been proposed to prevent progression of aneurysmal disease. These include hemodynamic management, inhibition of inflammation, and protease inhibition. The American College of Cardiology/American Heart Association clinical practice guidelines rules of evidence have helped to define strength of evidence to support these approaches. Level A evidence (from large randomized trials) is available to indicate that observation of small aneurysms in men is safe up to a size of 5.5 cm and that propranolol does not inhibit aneurysm expansion. Level B evidence (from small randomized trials) suggests that roxithromycin or doxycycline will decrease the rate of aneurysm expansion. A number of studies agree that tobacco use is associated with an increased rate of aneurysm expansion. Level B and C evidence is available to suggest that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may inhibit aneurysm expansion. There are animal data but no human data demonstrating that angiotensin-converting enzyme inhibitors or losartan, an angiotensin receptor blocker, will decrease the rate of AAA expansion. A pharmacological agent without important side effects that inhibited aneurysm expansion could change current approaches to aneurysm treatment. Additional studies are needed to clarify the potential role of doxycycline, roxithromycin, and statin therapy in the progression of aneurysmal disease.

Abstract

Changes in arterial wall composition and function underlie all forms of vascular disease. The fundamental structural and functional unit of the aortic wall is the medial lamellar unit (MLU). While the basic composition and organization of the MLU is known, three-dimensional (3D) microstructural details are tenuous, due (in part) to lack of three-dimensional data at micro- and nano-scales. We applied novel electron and confocal microscopy techniques to obtain 3D volumetric information of aortic medial microstructure at micro- and nano-scales with all constituents present. For the rat abdominal aorta, we show that medial elastin has three primary forms: with approximately 71% of total elastin as thick, continuous lamellar sheets, 27% as thin, protruding interlamellar elastin fibers (IEFs), and 2% as thick radial struts. Elastin pores are not simply holes in lamellar sheets, but are indented and gusseted openings in lamellae. Smooth muscle cells (SMCs) weave throughout the interlamellar elastin framework, with cytoplasmic extensions abutting IEFs, resulting in approximately 20 degrees radial tilt (relative to the lumen surface) of elliptical SMC nuclei. Collagen fibers are organized as large, parallel bundles tightly enveloping SMC nuclei. Quantification of the orientation of collagen bundles, SMC nuclei, and IEFs reveal that all three primary medial constituents have predominantly circumferential orientation, correlating with reported circumferentially dominant values of physiological stress, collagen fiber recruitment, and tissue stiffness. This high resolution three-dimensional view of the aortic media reveals MLU microstructure details that suggest a highly complex and integrated mural organization that correlates with aortic mechanical properties.

Abstract

To determine risk factors predictive of microemboli found on diffusion-weighted magnetic resonance imaging (DW-MRI) following carotid angioplasty and stenting (CAS) with distal protection and carotid endarterectomy (CEA).A retrospective review was conducted of all carotid interventions at a single institution between 2004 and 2006. In that time frame, 64 carotid interventions (34 CAS, 30 CEA) were performed in 63 male patients (mean age 69.5 years, range 52 to 91) with DW-MRI scans available for review. Patient characteristics, including age, gender, smoking history, diabetes mellitus, hypertension, hyperlipidemia, obesity (body mass index >30), coronary artery disease (CAD), chronic obstructive pulmonary disease, peripheral vascular disease, and atrial fibrillation, were documented. For the CAS patients, anatomical and procedural characteristics, including fluoroscopy time, contrast volume, performance of an arch angiogram, and lesion anatomy, were recorded. Bivariate analyses were performed to determine which parameters were associated with the occurrence of acute postprocedural microemboli found on DW-MRI by 2 blinded neuroradiologists.Twenty-four (71%) of the 34 CAS patients and 1 (3%) of the 30 CEA patients demonstrated new cerebral microemboli postoperatively. In the bivariate analyses of all patient, anatomical, and procedural characteristics, only a history of CAD was associated with an increased risk of microemboli; 20 (80%) of the 25 patients who had postprocedure microemboli had CAD compared to 18 (46%) of 39 patients without microemboli (p=0.007). Twenty (53%) of the 38 (59%) patients with CAD developed microemboli compared to 5 (19%) of the 26 patients without CAD (p=0.007). All other patient, procedural, and anatomical characteristics were not found to be independent risk factors predictive of postprocedure microemboli.CAS with distal protection carries a significantly greater risk for developing new microemboli compared to CEA. Of all the risk factors analyzed, only a history of CAD emerged as an independent risk factor for the development of microemboli following carotid intervention. This finding may influence the decision to perform CAS in patients deemed high risk solely due to the presence of CAD.

Abstract

The relative safety of percutaneous carotid interventions remains controversial. Few studies have used diffusion-weighted magnetic resonance imaging (DW-MRI) to evaluate the safety of these interventions. We compared the incidence and distribution of cerebral microembolic events after carotid angioplasty and stenting (CAS) with distal protection to standard open carotid endarterectomy (CEA) using DW-MRI.From November 2004 through August 2006, 69 carotid interventions (27 CAS, and 42 CEA) were performed in 68 males at a single institution. Pre- and postprocedure DW-MRI exams were obtained on each patient undergoing CAS and the 20 most recent CEA operations. These 46 patients (47 procedures as one patient underwent bilateral CEAs in a staged fashion) constitute our study sample, and the hospital records of these patients (27 CAS and 20 CEA) were retrospectively reviewed. The incidence and location of acute, postprocedural microemboli were determined using DW-MRIs and assessed independently by two neuroradiologists without knowledge of the subjects' specific procedure.Nineteen CAS patients (70%, 95% confidence interval [CI]: 42%-81%) demonstrated evidence of postoperative, acute, cerebral microemboli by DW-MRI vs none of the CEA patients (0%, 95% CI: 0%-17%) (P < .0001). Of the 19 CAS patients with postoperative emboli, nine (47%) were ipsilateral to the index carotid lesion, three (16%) contralateral, and seven (36%) bilateral. The median number of ipsilateral microemboli identified in the CAS group was 1 (interquartile ranges [IQR]: 0-2, range 0-21). The median number of contralateral microemboli identified in the CAS group was 0 (IQR: 0-1, range 0-5). Three (11%) CAS patients experienced temporary neurologic sequelae lasting less than 36 hours. These patients suffered 12 (six ipsilateral and six contralateral), 20 (19 ipsilateral and one contralateral), and zero microemboli, respectively. By univariate analysis, performing an arch angiogram prior to CAS was associated with a higher risk of microemboli (median microemboli 5 vs none, P =.04)Although our early experience suggests that CAS may be performed safely (no permanent neurologic deficits following 27 consecutive procedures), cerebral microembolic events occurred in over two-thirds of the procedures despite the uniform use of distal protection. Open carotid surgery in this series seems to offer a lower risk of periprocedural microembolic events detected by DW-MRI.

Abstract

Accumulation of iron in excess of physiologic requirements has been implicated in risk of cardiovascular disease because of increased iron-catalyzed free radical-mediated oxidative stress.To test the hypothesis that reducing body iron stores through phlebotomy will influence clinical outcomes in a cohort of patients with symptomatic peripheral arterial disease (PAD). Design, Setting, andMulticenter, randomized, controlled, single-blinded clinical trial based on the Iron (Fe) and Atherosclerosis Study (FeAST) (VA Cooperative Study #410) and conducted between May 1, 1999, and April 30, 2005, within the Department of Veterans Affairs Cooperative Studies Program and enrolling 1277 patients with symptomatic but stable PAD. Those with conditions likely to cause acute-phase increase of the ferritin level or with a diagnosis of visceral malignancy within the preceding 5 years were excluded. Analysis was by intent-to-treat.Patients were assigned to a control group (n = 641) or to a group undergoing reduction of iron stores by phlebotomy with removal of defined volumes of blood at 6-month intervals (avoiding iron deficiency) (n = 636), stratified by hospital, age, and baseline smoking status, diagnosis of diabetes mellitus, ratio of high-density to low-density lipoprotein cholesterol level, and ferritin level.The primary end point was all-cause mortality; the secondary end point was death plus nonfatal myocardial infarction and stroke.There were no significant differences between treatment groups for the primary or secondary study end points. All-cause deaths occurred in 148 patients (23%) in the control group and in 125 (20%) in the iron-reduction group (hazard ratio (HR), 0.85; 95% confidence interval (CI), 0.67-1.08; P = .17). Death plus nonfatal myocardial infarction and stroke occurred in 205 patients (32%) in the control group and in 180 (28%) in the iron-reduction group (HR, 0.88; 95% CI, 0.72-1.07; P = .20).Reduction of body iron stores in patients with symptomatic PAD did not significantly decrease all-cause mortality or death plus nonfatal myocardial infarction and stroke.Clinicaltrials.gov Identifier: NCT00032357.

Abstract

Allometric scaling laws relate structure or function between species of vastly different sizes. They have rarely been derived for hemodynamic parameters known to affect the cardiovascular system, e.g., wall shear stress (WSS). This work describes noninvasive methods to quantify and determine a scaling law for WSS. Geometry and blood flow velocities in the infrarenal aorta of mice and rats under isoflurane anesthesia were quantified using two-dimensional magnetic resonance angiography and phase-contrast magnetic resonance imaging at 4.7 tesla. Three-dimensional models constructed from anatomic data were discretized and used for computational fluid dynamic simulations using phase-contrast velocity imaging data as inlet boundary conditions. WSS was calculated along the infrarenal aorta and compared between species to formulate an allometric equation for WSS. Mean WSS along the infrarenal aorta was significantly greater in mice and rats compared with humans (87.6, 70.5, and 4.8 dyn/cm(2), P < 0.01), and a scaling exponent of -0.38 (R(2) = 0.92) was determined. Manipulation of the murine genome has made small animal models standard surrogates for better understanding the healthy and diseased human cardiovascular system. It has therefore become increasingly important to understand how results scale from mouse to human. This noninvasive methodology provides the opportunity to serially quantify changes in WSS during disease progression and/or therapeutic intervention.

Abstract

Abdominal aortic aneurysms (AAAs) are a common and lethal disease of the elderly. 'Atherosclerotic' aneurysms occur far more frequently in the caudal or infrarenal segment, a localization influenced at least in part by site-specific hemodynamic conditions. Alterations in aortic flow and wall shear stress modify AAA disease progression in small animal models and may explain increased prevalence in certain at-risk patient populations. If a specific hemodynamic risk profile can be established, anti-aneurysmal lower extremity exercise protocols or the development of molecular interventions that mimic the benefits induced by exercise may prove effective in reducing progression of small AAAs or limiting continued remodeling or expansion following endovascular exclusion.

Abstract

Abdominal aortic aneurysm (AAA) is a common and frequently lethal disease of older Americans. No medical therapy has been proven effective in retarding progression of small AAAs prior to surgical repair. With the emerging ability of magnetic resonance (MR) flow imaging and MR-based computational analysis to define aortic hemodynamic conditions, and bio-imaging strategies to monitor aortic inflammation real time in vivo, the opportunity now exists to confirm the potential value of medical interventions such as supervised exercise training as first line therapy for small AAA disease.

Abstract

Our previous study demonstrated that high flow conditions stimulated cell proliferation in the aortic wall in a rat model of abdominal aortic aneurysm (AAA), and we speculated that there is a possible relation between medial cell density and aortic wall integrity. In the present study we delivered the basic fibroblast growth factor (bFGF) gene to the aortic wall of a rat AAA model and evaluated the effects of growth factor-enhanced smooth muscle cell (SMC) proliferation on aneurysm progression.AAA was induced in rats by means of infusion of porcine pancreatic elastase. Immediately after elastase infusion the abdominal aorta was filled with an expression plasmid vector containing the bFGF gene (bFGF group) or LacZ gene (control group); then gene transfer to the aortic wall was carried out with an in vivo electroporation method. The animals were killed 7 days after treatment, and the aneurysm was measured. The numbers of SMCs, macrophages, and endothelial cells were counted with immunostaining, and cell replication was evaluated with bromodeoxyuridine (BrdU) staining.Aneurysm diameter in the bFGF group was significantly smaller than that in the control group (4.6 +/- 0.3 mm vs 6.5 +/- 1.4 mm; P

Abstract

The purpose of this study was to utilize an objective endpoint analysis of aneurysm treatment, which is based on the primary objective of aneurysm repair, and to apply it to a consecutive series of patients undergoing open and endovascular repair.Aneurysm-related death was defined as any death that occurred within 30 days of primary aneurysm treatment (open or endovascular), within 30 days of a secondary aneurysm or graft-related treatment, or any death related to the aneurysm or graft at any time following treatment. We reviewed 417 consecutive patients undergoing elective infrarenal aortic aneurysm repair: 243 patients with open repair and 174 patients with endovascular repair.There was no difference between the groups (open vs endovascular) with regard to mean age +/- standard deviation (73 +/- 8 years vs 74 +/- 8 years) or aneurysm size (64 +/- 2 mm vs 58 +/- 10 mm) (P = not significant [NS]). The 30-day mortality for the primary procedure after open repair was 3.7% (9/243) and after endovascular repair was 0.6% (1/174, P

Abstract

To compare the outcomes of open versus endovascular repair of abdominal aortic aneurysm (AAA) in a cohort of patients who fulfill morphological criteria for endovascular repair.A retrospective review of 229 consecutive AAA patients treated over a 3-year period identified 149 patients who were candidates for endovascular repair based on preoperative computed tomography and angiography. Of the 149 patients, 79 (68 men; mean age 74 +/- 8 years) underwent endovascular repair with the AneuRx stent-graft; the remaining 70 (56 men; mean age 72 +/- 8 years) had open repair. Short-term outcome measures were 30-day mortality and procedure-related morbidity, length of stay in the intensive care unit and hospital, intraoperative blood loss, interval to oral diet, and time to ambulation. Long-term outcome measures included death and secondary procedures.There was no difference in the 30-day mortality between endovascular repair (2, 2.5%) and open repair (2, 2.9%), even though endovascular patients had more comorbidities (p<0.05). Overall length of stay was reduced for endovascular patients (3.9 +/- 2.4 days versus 7.7 +/- 3.1 days for surgical patients, p<0.0001). Fewer endograft patients had complications (24% versus 40% for open repair, p<0.05), and the severity of these complications was less, as evidenced by the shorter hospital stays for endovascular patients with complications compared to conventionally treated patients with complications (6.7 +/- 2.4 days versus 22.5 +/- 35.2 days, p<0.05). There were no aneurysm ruptures or late surgical conversions in either group.Patients with AAA who were endograft candidates but who were treated with open repair experienced more morbidity and had more complications than patients treated with stent-grafts. Despite increased comorbidities in the endograft patients, there was no increase in mortality compared to open repair. Both treatments required secondary procedures and appeared to be equally effective in preventing aneurysm rupture up to 3 years.

Abstract

Intraabdominal anastomotic pseudoaneurysms continue to be a late complication of aortic reconstructive procedures. Early surgical repair is critical but is associated with high operative mortality rates. We present a patient who was diagnosed with a distal anastomotic pseudoaneurysm 13 months after transabdominal repair of a symptomatic abdominal aortic aneurysm. Because of the poor operative risk, the patient was considered for a less invasive approach and underwent coil embolization of the abdominal aortic anastomotic pseudoaneurysm. The patient remains without recurrence of pseudoaneurysm 3.5 years later.

Abstract

The purpose of this study was to determine the impact of an endovascular stent-graft program on vascular training in open aortic aneurysm surgery.The institutional and vascular surgery fellow experience in aortic aneurysm repair during a 6-year period was reviewed. The 3-year period before introduction of endovascular repair was compared with the 3-year period after introduction of endovascular repair. All patients undergoing abdominal aortic aneurysm (AAA) or thoracoabdominal aortic aneurysm repairs were entered prospectively into a vascular registry and retrospectively analyzed to evaluate the changing patterns in aortic aneurysm treatment and surgical training.Between July 1994 and June 2000, a total of 588 patients with AAA or thoracoabdominal aneurysms were treated at Stanford University Medical Center. There were 296 (50%) open infrarenal AAA repairs, 87 (15%) suprarenal AAA repairs, 47 (8%) thoracoabdominal aneurysm repairs, and 153 (26%) endovascular stent-grafts. The total number of aneurysms repaired per year by vascular fellows before the endovascular program was 71.3 +/- 4.9 (range, 68-77) and increased to 124.7 +/- 35.6 (range, 91-162) after introduction of endovascular repair (P

Abstract

Aortic stent grafting is gaining acceptance rapidly as a durable and effective alternative to open surgery for abdominal aortic aneurysms (AAA). Unlike follow-up after open surgical procedures, postplacement surveillance protocols are necessary to ensure long-term freedom from device failure or aneurysm rupture. Surveillance protocols incorporating duplex scanning are effective and may reduce overall postplacement expenses. Specific device or patient anatomic features may be prone to failure, and familiarity with each approved device is a prerequisite to the performance of effective device surveillance studies. Mechanisms of failure of aneurysm exclusion after device placement, or "endoleak," have been described and categorized. Endoleak significance is directly related to location, duration, and influence on AAA diameter. Endoleak type also determines when and whether additional interventions are indicated. Future progress in endovascular AAA exclusion will depend in large part on the reliability and utility of cost-effective postprocedure surveillance protocols incorporating duplex ultrasound imaging.

Abstract

The authors present an unusual case of a spontaneous carotid-cutaneous fistula occurring as a late complication 4 years after radical neck dissection and postoperative radiation therapy for tonsillar squamous cell carcinoma in a 50-year-old patient. The etiologic factors predisposing patients to carotid artery rupture following radical neck dissection and a surgical option for carotid artery reconstruction instead of ligation are discussed.

Abstract

To evaluate of the impact of endovascular aneurysm repair on the rate of open surgical repair and on the overall treatment of abdominal aortic aneurysms (AAAs).All patients with AAA who were treated during two consecutive 40-month periods were reviewed. During the first period, only open surgical repair was performed; during the subsequent 40 months, endovascular repair and open surgical repair were treatment options.A total of 727 patients with AAA were treated during the entire period. During the initial 40 months, 268 patients were treated with open surgical repair, including 216 infrarenal (81%), 43 complex (16%), and 9 ruptured (3%) aortic aneurysms. During the subsequent 40 months, 459 patients with AAA were treated (71% increase). There was no significant change in the number of patients undergoing open surgical repair and no significant difference in the rate of infrarenal (238 [77%]) and complex (51 [16%]) repairs. A total of 353 patients were referred for endovascular repair. Of these, 190 (54%) were considered candidates for endovascular repair based on computed tomography or arteriographic morphologic criteria. Analyzing a subgroup of 123 patients, the most common primary reasons for ineligibility for endovascular repair were related to morphology of the neck in 80 patients (65%) and of the iliac arteries in 35 patients (28%). A total of 149 patients underwent endovascular repair. Of these, the procedure was successful in 147 (99%), and 2 (1%) patients underwent surgical conversion. The hospital death rate was 0%, and the 30-day death rate was 1%. During a follow-up period of 1 to 39 months (mean 12 +/- 9), 21 secondary procedures to treat endoleak (20) or to maintain graft limb patency (1) were performed in 17 patients (11%). There were no aneurysm ruptures or aneurysm-related deaths.Endovascular repair appears to have augmented treatment options rather than replaced open surgical repair for patients with AAA. Patients who previously were not candidates for repair because of medical comorbidity may now be safely treated with endovascular repair.

Abstract

The purpose of this study was to determine the rate of eligibility among patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair and to examine the effect of an endovascular program on the institutional pattern of AAA repair.All patients evaluated for endovascular AAA repair since the inception of an endovascular program were reviewed for determination of eligibility rates and eventual treatment. Open AAA repairs were categorized as simple (uncomplicated infrarenal), complex (juxtarenal, suprarenal, thoracoabdominal, infected), or ruptured, and their rates before and after initiation of an endovascular program were compared.Over 3 years, 324 patients were considered for endovascular AAA repair; 176 (54%) were candidates, 138 (43%) were not candidates, and 10 (3%) did not complete the evaluation. The rate of eligibility increased significantly from 45% (66/148 patients) during the first half of this period to 63% (110/176 patients) during the second half (P

Abstract

Arterial diameter changes in response to flow. Chronic flow-mediated arterial enlargement may be mediated through metalloproteinase activity in the extracellular matrix of the arterial wall. We examined flow-mediated enlargement in the setting of increasing competitive matrix metalloproteinase (MMP) inhibition and with respect to gelatinase A and B expression and activity.Left common femoral arteriovenous fistulas (AVFs) were created in dose-response (52) and time course (34) cohorts of rats. Dose-response rats received either vehicle alone or 12.5, 25, or 37. 5 mg/kg b.i.d. RS 113,456, a competitive MMP inhibitor. Heart rate, blood pressure, and weight were measured at intervals following AVF construction. Aortic and common iliac diameters were measured on postoperative day (POD) 21. Untreated time course rats were sacrificed on PODs 0 (no AVF), 3, 7, 14, and 21. Aortic diameter was measured and the vessels were harvested for tissue analysis. Equal amounts of aortic RNA underwent reverse transcription and polymerase chain reaction with primers for MMP-2, MMP-9, and GAPDH. Zymography was performed on iliac artery tissue to measure gelatinolytic activity.A significant, stepwise reduction in flow-mediated aortic and left common iliac enlargement following left femoral AVF creation was noted with progressively higher doses of RS 113,456 without apparent hemodynamic or toxic effects. Right common iliac diameter was unchanged. Over 21 days following AVF creation, there was an upward trend in expression and activity for MMP-2 not evident for MMP-9.Flow-mediated arterial enlargement is limited by competitive MMP inhibition in a dose-dependent fashion. MMP-dependent flow-mediated enlargement may involve differential expression and activity of MMP-2 and MMP-9.

Modular systems in the treatment of abdominal aortic aneurysms: lessons learned in the development of designer endografts.Seminars in vascular surgeryHarris, E. J.1999; 12 (3): 170-175

Abstract

Treatment of abdominal aortic aneurysms with endoluminal stent-grafts is gaining increased interest. Since the original home-made stent-graft was developed in 1991, a multitude of devices have been developed for this treatment. Modular endografts have evolved during this time and offer several significant advantages. Thorough preoperative imaging and assessment is critical to the success of this new therapy for abdominal aortic aneurysms. Lessons learned during the development of the Medtronic AneuRx endograft and its early clinical trials are discussed.

Abstract

The authors attempted to determine whether the T2 relaxation time of superior mesenteric vein (SMV) blood would decrease in patients with chronic mesenteric ischemia after a meal.Thirty-two patients without chronic mesenteric ischemia and eight patients with symptomatic chronic mesenteric ischemia underwent magnetic resonance (MR) imaging. All examinations were performed with a 1.5-T unit, a modified Carr-Purcell-Meiboom-Gill sequence, final section-selective pulse of 180 degrees, and spiral readout gradients. Measurements of SMV blood T2 were obtained after at least 6 hours of fasting and 15 and 35 minutes after ingestion of 240 mL of a liquid nutritional supplement. Maximal change of the SMV blood T2 was expressed as a percentage of the fasting T2 in all patients.In control patients, SMV blood T2 increased postprandially by 9.4% +/- 1.3 (95% confidence level; range, 6.8%-11.9%) (data range, -7.3% to 25.6%) compared with fasting T2. In symptomatic patients, SMV blood T2 decreased postprandially by 15.8% +/- 2.2 (95% confidence level; range, -20.1% to -10.7%) (data range, -7.9% to -25.3%). The difference between the two groups was statistically significant (P < .0001 by Student unpaired t test).Measurement of SMV blood T2 is a promising test for chronic mesenteric ischemia diagnosis. Therefore, conversion of T2 measurements to estimate oxygen saturation may not be necessary for all cases of this clinical indication.

Abstract

Patients with recurrent carotid artery stenosis are sometimes referred for carotid angioplasty and stenting because of reports that carotid reoperation has a higher complication rate than primary carotid endarterectomy. The purpose of this study was to determine whether a difference exists between outcomes of primary carotid endarterectomy and reoperative carotid surgery.Medical records were reviewed for all carotid operations performed from September 1993 through March 1998 by vascular surgery faculty at a single academic center. The results of primary carotid endarterectomy and operation for recurrent carotid stenosis were compared.A total of 390 operations were performed on 352 patients. Indications for primary carotid endarterectomy (n = 350) were asymptomatic high-grade stenosis in 42% of the cases, amaurosis fugax and transient ischemic symptoms in 35%, global symptoms in 14%, and previous stroke in 9%. Indications for reoperative carotid surgery (n = 40) were symptomatic recurrent lesions in 50% of the cases and progressive high-grade asymptomatic stenoses in 50%. The results of primary carotid endarterectomy were no postoperative deaths, an overall stroke rate of 1.1% (three postoperative strokes, one preoperative stroke after angiography), and no permanent cranial nerve deficits. The results of operations for recurrent carotid stenosis were no postoperative deaths, no postoperative strokes, and no permanent cranial nerve deficits. In the primary carotid endarterectomy group, the mean hospital length of stay was 2.6 +/- 1. 1 days and the mean hospital cost was $9700. In the reoperative group, the mean length of stay was 2.6 +/- 1.5 days and the mean cost was $13,700. The higher cost of redo surgery is accounted for by a higher preoperative cerebral angiography rate (90%) in redo cases as compared with primary endarterectomy (40%).In this series of 390 carotid operations, the procedure-related stroke/death rate was 0.8%. There were no differences between the stroke-death rates after primary carotid endarterectomy and operation for recurrent carotid stenosis. Operation for recurrent carotid stenosis is as safe and effective as primary carotid endarterectomy and should continue to be standard treatment.

Abstract

We administered a specific, nonselective matrix metalloproteinase (MMP) inhibitor (RS-113,456) to examine the effect of MMP inhibition on flow-mediated arterial enlargement in a rodent arteriovenous fistula (AVF) model.Four groups of male Sprague-Dawley rats were created: sham (sham operated; n = 10), control (2.0 mm left common femoral AVF alone; n = 16), vehicle (AVF plus 0.5 mL vehicle orally twice a day; n = 20), and treatment (AVF plus 25 mg/kg RS-113,456 in 0.5 mL vehicle orally twice a day; n = 16). Heart rate, mean arterial pressure, and body weight were recorded on postoperative days 0, 7, 14, and 21. On day 21, AVF patency was confirmed, the infrarenal aorta and common iliac arteries were exposed, blood flow velocity and external diameter were measured, and wall shear stress (WSS) was calculated. Analysis was performed by paired, two-tailed Student t test, one-way analysis of variance, and the Bonferroni/Dunn procedure for post hoc testing.Heat rate, mean arterial pressure, and weight did not vary at any time between groups. Aortic and left iliac diameter was larger in the AVF groups than in sham groups (P < .001), and control and vehicle groups were larger than treatment groups (P < .0001). Changes in aortic and left iliac flow were also significant (AVF was more than sham and control, and vehicle was more than treatment). No difference in aortic and left iliac artery velocity and WSS or right iliac diameter, velocity, flow, or WSS was observed between groups.MMP inhibition diminishes flow-mediated arterial enlargement in the rat AVF model.

Abstract

Advances in the care and rehabilitation of patients with spinal cord injuries (SCI) have resulted in extended survival following injury. Increasingly, we are faced with difficult chronic lower extremity ischemic complications in SCI patients. Recognizing limitations associated with amputation in these nonambulatory patients, we report the preliminary results of a program of selective limb salvage via arterial reconstructive surgery. Retrospective chart review was performed on the records of the Veterans Affairs Palo Alto Health Care System SCI unit. Since 1989, 15 revascularization procedures were identified in 10 SCI patients. All patients suffered from ischemic ulceration and/or gangrene. Procedures performed included femorotibial bypass (8), aortofemoral bypass (4), femoro-femoral bypass (2), and axillobifemoral bypass (AXF) (1). All patients were men. The mean age was 56 (range 43-73). Follow-up was available on 10 procedures performed in seven patients since 1992. Mean follow-up was 17 months. One patient died 3 months following distal bypass. The AXF occluded within 1 month. One distal bypass occluded in the immediate postoperative period and could not be salvaged. All other grafts remain patent, and all wounds have healed following successful bypass. One patient developed pressure ulceration following AXF grafting due to postoperative upper extremity limitations. No other complications were encountered. Standard arterial reconstructive procedures can be performed safely and successfully in SCI patients, despite diminished limb blood flow due to inactivity, and atrophic arteries, muscle, and fascia. Axillobifemoral bypass grafting may not be suitable in SCI due to requirements for upper extremity-based mobility. Confirmation of benefit of limb salvage versus amputation awaits comparison between patients eligible for either procedure.

Abstract

To determine if dogs and humans with chronic mesenteric ischemia demonstrate a decrease in the percentage of oxygenated hemoglobin (%HbO2) in the superior mesenteric vein (SMV) after a meal.In 10 dogs, ameroid rings were surgically implanted around the superior mesenteric arteries to create gradual stenosis. Pre- and postoperative angiograms and pre- and postprandial magnetic resonance (MR) oximetry measurements of the SMV %HbO2, with flow-independent T2 measurements of venous blood, were obtained at different times. In 10 patients with atherosclerotic disease and six patients with symptomatic chronic mesenteric ischemia, the same measurements were obtained after at least 6 hours of fasting and at 15, 35, and 45 minutes after ingestion of a liquid nutritional supplement.In seven dogs, the postprandial SMV %HbO2 increased an average of 2.5% +/- 0.8 before surgery and decreased an average of 6.3% +/- 2.1 when hemodynamically significant (>70%) stenosis of the superior mesenteric artery developed 7-14 days after surgery. In the 10 patients without ischemia, the SMV %HbO2 increased by 4.6% +/- 0.6, whereas in the symptomatic patients a postprandial decrease of 8.8% +/- 0.7 occurred (P < .0001).Measurement of the SMV %HbO2 with MR oximetry is a promising test for diagnosis of chronic mesenteric ischemia.

Abstract

Therapeutic options for subclavian vein thrombosis (SVT) include anticoagulation, thrombolysis, endovascular repair, and direct surgical intervention. The most effective method of treatment remains undetermined. We reviewed our institutional experience over 7 years with SVT patients to compare the results of treatment based on etiology of thrombosis. Nineteen patients suffered SVT secondary to malignancy, catheter placement, radiation, or hypercoagulability. Thirteen were Paget-Schroetter (PSS), or primary effort-related SVT. Patients with dialysis access procedures were excluded. Thrombolysis was initiated in 31/32 patients. Success was defined as complete obliteration of clot. Adjunctive treatment to relieve external compression or improve lumenal contour was performed on 16/32 patients (eight PSS, eight secondary SVT). Success of adjunctive treatment was defined as return to baseline activity without symptoms. Objective follow up (venography or duplex scanning) was included when available. Adjunctive treatment included balloon angioplasty (6), stent placement (5), first rib resection and scalenectomy (4), and vein reconstruction (4). Initial treatment success with thrombolysis was achieved in 26/31 patients (84%). Angioplasty failed in three PSS and three secondary SVT patients. Stent placement was successful in 2/5 patients (both secondary SVT). Surgery was performed only on PSS patients: first rib resection and scalenectomy succeeded 4/4 times, vein reconstruction 2/4. Twenty-eight patients were given long-term therapy with oral anticoagulation with good long-term results. Seven patients experienced complications, including one death. Results of SVT therapy including thrombolysis and oral anticoagulation are very good. Angioplasty and stent placement in secondary SVT patients appears to add little long term benefit. Surgery may improve outcome in selected PSS patients, although the additional benefit could not be determined by the design of this study. Evaluation and treatment limited only to PSS excludes the majority of SVT patients.

Abstract

The authors tested the hypothesis that changes in oxygen saturation (%HbO2) in the superior mesenteric vein (SMV), as measured with in vivo magnetic resonance (MR) oximetry, correlate with the degree of acute superior mesenteric artery (SMA) flow reduction.Ten mongrel dogs were studied. A catheter was inserted into the SMV, and a perivascular ultrasonic flow probe and an adjustable mechanical occluder were placed around the SMA. MR oximetry was carried out at the resting state and after the SMA was constricted to predetermined levels (0%-75% of initial flow). In seven dogs, SMV blood samples were obtained immediately before and after each MR measurement; %HbO2 was measured simultaneously by using an oximeter. With linear regression analysis, the SMV %HbO2 measurements obtained at MR imaging were compared with those obtained at oximetry. With a logistic model, MR imaging changes in SMV %HbO2 were compared with the degree of SMA flow reduction.SMV %HbO2 measurements obtained with MR imaging correlated well with those obtained with oximetry (r = .97). Changes in SMV %HbO2 measured at MR imaging also correlated well with the degree of SMA flow reduction, as determined with a logistic model (P = .01).Noninvasive in vivo MR measurements of SMV %HbO2 can be used to determine the degree of acute SMA flow reduction with a high degree of accuracy in a canine model.

Abstract

Superior mesenteric blood flow in the fasting and postprandial state in humans can be measured accurately by cine phase-contrast (CPC) magnetic resonance (MR) imaging. Postprandial flow changes associated with mesenteric arterial occlusive disease (MAOD) are unknown.We used CPC MR imaging to measure fasting and postprandial blood flow in the superior mesenteric artery (SMA) and vein (SMV) in 22 patients (mean age, 69 years) with aortic occlusive disease and MAOD and compared the results with similar measurements in 8 younger, asymptomatic volunteers (mean age, 34 years). All 22 patients had stenosis or occlusion of the splanchnic or pelvic arteries demonstrated by contrast aortography; 19 were asymptomatic and 3 had symptoms of chronic mesenteric ischemia. Mean fasting blood flow was higher in patients (4.5 mL.kg-1.min-1) than in volunteers (2.3 mL.kg-1.min-1; P < .01). However, postprandial hyperemia (mean percentage change in SMV blood flow) was less in the asymptomatic (70%; P < .001) and symptomatic patients (29%; P < .01) than in the volunteers. Postprandial SMV flow was similar to SMA flow in the patients but was significantly greater than SMA flow in the volunteers (P < .005).Postprandial mesenteric hyperemia is reduced in older patients with MAOD. The role of aging alone has not been determined. Fasting and postprandial flow changes in these patients may predict the onset of chronic mesenteric ischemia.

Abstract

Many surgeons advocate uniform performance of operative completion arteriography after leg bypass surgery to ensure technical success and to optimize short- and intermediate-term graft patency. To determine the impact of this practice on the outcome of reversed-vein bypass surgery and associated patient charges, we reviewed our series of consecutive nonemergent leg bypass procedures. Ninety-three infrainguinal bypass procedures were performed in 80 patients (76 men and 4 women) from September 1991 to August 1994. The patients' average age was 67 years (range, 30 to 92 years). Follow-up (mean, 113.1 months; range, 1 to 36 months) was available on 91 grafts (97%). Indications for surgery included limb salvage in 75 cases, claudication in 12 cases, and popliteal aneurysm exclusion in 6 cases. All patients survived surgery. Primary graft patency rates as determined by life-table analysis were 87%, 81%, 78%, and 78% at 6 months and at 1, 2, and 3 years, respectively. Limb-salvage rates were 95%, 91%, 87% and 87% at the same intervals. Bypass procedures were divided into two groups. The 25 grafts in group 1 were evaluated with inspection, continuous-wave Doppler insonation, and routine completion arteriography. The 68 grafts in group 2 were evaluated by inspection and insonation alone. Fourteen grafts occluded after surgery (average, 5 months; range, 1 to 12 months), five in group 1 and nine in group 2. The likelihood of graft occlusion was similar in both groups (p = 0.42). The optimal method of confirming technical adequacy after bypass surgery in the clinically satisfactory graft remains uncertain. Charges for completion arteriography at our institution average $700, including 15 minutes of additional operative time. In our experience, these charges do not appear to be justified by improved short- or intermediate-term graft patency rates in reversed-vein grafts when completion arteriography is performed.

Abstract

To evaluate the use of measurements of blood flow in the superior mesenteric vein (SMV) and superior mesenteric artery (SMA) simultaneously acquired with phase-contrast cine magnetic resonance (MR) imaging for diagnosing chronic mesenteric ischemia.Simultaneous measurements of flow in the SMV and SMA were obtained in six healthy volunteers and eight patients with angiographically proved SMA stenosis (six asymptomatic, two symptomatic). Flow dynamics in both vessels were correlated with the degree of arterial disease seen at angiography and with the presence or absence of ischemic symptoms.Postprandial SMV and SMA flow increased substantially less in patients with atherosclerosis than in volunteers. Comparison of simultaneous SMV and SMA flow measurements provided more information about collateral flow to and from the mesenteric circulation than did either the SMV or SMA flow measurement alone.Simultaneous SMV and SMA flow measurement with cine phase-contrast MR imaging may be useful in diagnosing and understanding chronic mesenteric ischemia.

Abstract

To evaluate the accuracy of magnetic resonance (MR) imaging in estimating oxygen saturation of blood (%HbO2) in the superior mesenteric vein (SMV) of a canine model in vivo.MR imaging was used to measure the T2 of blood in samples obtained via a catheter placed in the SMV in seven mongrel dogs. %HbO2 was measured with a reflectance oximeter. These measurements were obtained at the resting state, during superior mesenteric artery occlusion, and after reperfusion. MR imaging and oximeter measurements were then compared by using linear regression analysis.Refocusing intervals (tau 180) of 12 and 24 msec were used for 17 and 18 %HbO2 measurements with MR imaging, respectively. With tau 180 of 12 msec, there was an excellent correlation between MR imaging measurements and oximeter measurements (r = .969). The intercept was 5.3% and the slope was 0.959. With tau 180 of 24 msec, r = .953, the intercept was 15.4%, and the slope was 0.817.Estimates of %HbO2 in the SMV with MR imaging are accurate in the range of most clinical interest.

Abstract

Autoantibodies to phospholipid (aPL) have been associated with vascular thromboses in cerebral, coronary, and peripheral venous and arterial sites. To date, no large cross-sectional study has examined the incidence of occurrence of aPL in patients with peripheral arterial disease.A cross-sectional study was performed with patients admitted for vascular surgery procedures to treat peripheral arterial disease for 23 months between January 1, 1990 and November 1, 1991. Consecutive patients were evaluated for the presence of aPL. Medical records for each patient were reviewed in detail, and historic, operative, and postoperative parameters were tabulated for relationship to the presence of aPL.Two hundred thirty-four patients underwent complete testing for aPL. All patients were receiving chronic aspirin therapy. This represented 86% of admissions. Antiphospholipid antibodies were detected in 60 patients (26%). No differences in age, sex, operation performed, or postoperative outcome were found between patients with and without aPL. However, patients with aPL were 1.8 times more likely to have undergone previous lower extremity (LE) vascular surgery than patients without aPL (95% confidence interval = 1.0 - 3.6, p = 0.047). Patients with aPL and previous LE vascular surgery were 5.6 times more likely to have had occlusion of that procedure than patients without aPL (95% confidence interval = 1.9 - 16.8, p = 0.03). The occluded previous LE procedures had a shorter duration of patency before occlusion in patients with aPL than in those without (mean duration of patency 17 months vs. 50 months, p < 0.003). Patients with occluded previous LE procedures and aPL were 4 times more likely to be female (95% C.I. = 1.4 - 11.3, p = 0.018).The incidence of aPL in vascular surgery patients is substantial. Vascular surgery patients with aPL are more likely to have failure of previous LE bypass procedures and to be female and the bypass failure occurs significantly more rapidly than in patients without aPL. Based on these data, testing of vascular surgery patients for aPL and investigation of alternative antithrombotic treatment regimens in patients with aPL appears warranted.

Abstract

In a group of patients with high-grade asymptomatic carotid artery stenosis, we prospectively determined the prevalence and radiological characteristics of clinically asymptomatic brain infarction evident on computed tomography. Risk factors and extent of carotid disease were also determined.Patients randomized into the Asymptomatic Carotid Atherosclerosis Study (ACAS) underwent a neurological history, a detailed stroke/transient ischemic attack questionnaire, and a detailed neurological examination. Computed tomography scans were examined by standardized criteria developed as part of a quality-control program supervised by a neuroradiologist. The presence, location, and size of all cerebral infarctions evident by computed tomography were determined.Among 1132 patients, 848 had no history of stroke or transient ischemic attack. One hundred twenty-six patients (15%) had a silent infarct; 95 (11%) had one, 24 (3%) had two, and 7 (1%) had three or more infarcts. The infarct size was small and deep for 117 patients (72%), less than one-half lobe for 45 (28%), and one-half to less than one lobe for 1 (0.5%). The silent infarcts were evenly distributed ipsilaterally and contralaterally to the study artery but were significantly more frequent in the right hemisphere (P < .05). Factors associated with silent infarction were abnormal gait (P < .001), abnormal deep tendon reflexes or plantar responses (P = .038), but not degree of carotid stenosis. Silent infarction was less frequent among this totally asymptomatic cohort (15%) compared with those with transient ischemic attacks (34/139, 25%; P < .001).Silent infarction in the setting of asymptomatic carotid stenosis is not uncommon, but silent infarctions are rarely sizable. The clinical significance of silent cerebral infarction in patients with asymptomatic carotid artery stenosis has yet to be established.

Abstract

The physiologic significance of endothelin remains incompletely defined. Procoagulant and antifibrinolytic activities are increased in hypoxic cultured human umbilical venous endothelial cells (HUVEC). We examined the effect of hypoxia on HUVEC endothelin-1 production in vitro to determine whether a correlation existed between the procoagulant and antifibrinolytic response to hypoxia previously observed and an increase in vasoconstrictor peptide secretion by hypoxic HUVEC.Cultured HUVEC were rendered hypoxic (PO2 = 40 mm Hg) or control (PO2 = 120 mm Hg) for 24 hours. Media were either standard, 5 gm glucose/L (high glucose), or contained 500 units superoxide dismutase/ml (SOD). Endothelin-like immunoreactivity for endothelin-1 (ET-IR) in conditioned media was measured by radioimmunoassay and expressed as mean femtomoles per milliliter (+/- SD) per 100,000 cells. Viability of HUVEC was assessed by trypan blue exclusion. Significance was determined by use of Student's t test.Conditioned media from hypoxic cells contained 76% more ET-IR than was found in control counterparts (p < 0.004). The addition of high glucose or SOD did not diminish ET-IR; a trend to higher ET-IR was present in both these groups versus standard media (303% and 226%, respectively, p < 0.03).Thus 24 hours of hypoxia caused an increase in conditioned-media ET-IR in cultured HUVEC. Because SOD or greater substrate availability did not diminish endothelin presence in conditioned media, it seems that hypoxic induction of endothelin-1 production or secretion is signaled in a fashion unrelated to cell toxicity from the hypoxic period.

Abstract

Seventeen arterial bypass procedures distal to the wrist have been performed in 13 men and two women at the Oregon Health Sciences University during the past 9 years. Ten patients had traumatic true or false aneurysms of the ulnar artery with digital embolization. Five patients with end-stage renal disease had severe hand and finger ischemia manifested by rest pain or digital ulceration resulting from widespread forearm and hand arterial occlusions. Patients with aneurysms of the ulnar artery underwent excision and reversed autogenous vein grafting (n = 11) from the distal ulnar artery in the forearm to the superficial palmar arch. All the patients with end-stage renal disease had severe occlusive disease of the forearm and hand arteries and underwent a variety of procedures including radial-radial bypass (n = 2), ulnar-ulnar bypass (n = 2), radial-radial bypass with takedown of a Brescia-Cimino fistula (n = 1), and brachial-radial bypass (n = 1). High-quality upper extremity and magnification hand arteriography was essential for operative planning and was available on all patients. Distal saphenous vein from the ankle or foot was the graft source in 16 procedures and basilic vein the source in one procedure. All operations were performed with headlight illumination, optical loupes, fine sutures, and microvascular instruments. There were no operative deaths or major complications. The mean follow-up period was 14 months. Of the 17 grafts, 16 remained patent by clinical and vascular lab criteria. The single occlusion occurred in an ulnar aneurysm bypass and was accompanied only by mild intolerance to cold.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract

Mesenteric artery duplex scanning appears promising for detection of splanchnic artery stenosis or occlusion or both in patients with symptoms suggestive of chronic intestinal ischemia. However, no specific duplex criteria have been developed for detection of mesenteric artery stenosis. We obtained mesenteric artery duplex scans and infradiaphragmatic lateral aortograms in 34 patients to determine duplex criteria for mesenteric stenosis. Seventy percent or greater angiographic stenosis was present in 10 superior mesenteric arteries and 16 celiac arteries. Duplex scans were reviewed to determine if celiac artery and superior mesenteric artery ratios of peak systolic velocities and end-diastolic velocities to peak aortic systolic velocity, as well as celiac artery and superior mesenteric artery peak systolic velocities and end-diastolic velocities alone, could predict a greater than or equal to 70% angiographic stenosis or occlusion or both. The results obtained by use of receiver operator curves indicated peak systolic velocity alone was an accurate predictor of splanchnic artery stenosis. Specifically, a peak systolic velocity greater than or equal to 275 cm/sec in the superior mesenteric artery and greater than or equal to 200 cm/sec in the celiac artery or no flow signal (superior mesenteric artery and celiac artery) predicted a 70% to 100% stenosis with sensitivity, specificity, and positive predictive values of 89%, 92%, and 80% for the superior mesenteric artery. Similar values for the celiac artery were 75%, 89%, and 85%, respectively. End-diastolic velocities or calculated velocity ratios conveyed no additional accuracy in predicting splanchnic artery stenosis.

Abstract

Sixty-two patients (39 men (63%), 23 women (27%), mean age 68 years) with multilevel lower extremity arterial occlusive disease underwent simultaneous inflow and outflow operative arterial repair consisting of aortofemoral bypass in 22 (35%), axillofemoral bypass in 17 (28%), femorofemoral bypass in 15 (24%), iliac endarterectomy in 7 (11%), and unilateral aortoiliac bypass in 1 (2%), combined with 69 outflow procedures (unilateral in 55 patients, 89%), including above-knee femoropopliteal in 12 (17%), below-knee femoropopliteal in 35 (51%), femoroinfrapopliteal in 20 (29%), popliteal tibial in 1 (1%), and femoropedal bypass in 1 (1%). Multiple criteria were used to identify patients with multilevel disease likely to benefit from multilevel procedures. The operations were performed by two operating teams in a median time of 240 minutes. Prosthetic grafts were used for eight (13%) distal bypasses, the remainder were autogenous vein. There was one operative death (1.8%). The mortality rate, morbidity rate, and operative time were not significantly different from a group of patients who underwent concurrent, isolated inflow operations (aortofemoral, axillobifemoral, femorofemoral bypass or iliac endarterectomy). Mean follow-up was 14.9 months (range, 0 to 120). The life-table primary patency for the inflow procedures was 92.6% at 24 months, the outflow was 94.9% at 24 months. Cumulative limb salvage was 90.9% at 48-month follow-up. All patients with claudication were relieved of their symptoms. We conclude that complete correction of multilevel disease can be accomplished with operative time, morbidity rate, and patency equal to that of single level repair. Multilevel procedures provide complete relief of symptoms in a higher percentage of patients than has been reported after single level repair.